Many types of essential oils, such as helichrysum, get hyped by bloggers despite the fact there’s very little research about them.
When you find one that has over 500 medical citations listed in the PubMed database, with more than a couple dozen of those being clinical studies, it’s probably worth your time to pay attention.
The one we’re talking about is eucalyptus.
Whether you prefer a big brand like Doterra, or a niche like De La Cruz, almost every manufacturer lists this among their 10 bestselling EOs. Given its versatility, it’s easy to understand why.
What is eucalyptus essential oil good for?
First and foremost, its pleasing scent is a quality women love. From aromatherapy to cleaning, there are many ways to put it to use around the home.
But it doesn’t just smell good!
Having antimicrobial properties, it’s a non-toxic ingredient for bolstering natural cleaning products. That’s why it’s a main ingredient in Plant Therapy’s popular Germ Fighter Synergy blend.
It has been studied for some expected – and some very unexpected – medical uses.
Please be aware however that any medical research discussed below is for informational purposes only. It is not to be used to diagnose, treat, cure, or prevent any disease. No medical benefits for this oil have been proven, but the research is fascinating to read nonetheless.
Can you eat it?
Title 21 governs food and drugs for the FDA and a couple other agencies (1).
Section 172.510 of that code is about flavoring agents and on the list, you will find Eucalyptus globulus leaves.
Those are considered safe to eat when they’re used as a flavor, meaning it’s added to other food and it’s not the primary ingredient. An edible example would be this Breathe Deep tea on Amazon.
There’s no such thing as edible or food grade eucalyptus oil, because it’s not generally recognized as safe (GRAS) for consumption by itself.
On the other hand, koalas are different story…
You may hear of people using a drop of the oil under tongue sublingually, or diluted in a glass of water. Even though that may not cause noticeable reactions, it’s not an approved or recommended use.
The reason the leaves are considered safe is because the volatile oils are only a tiny percentage of them; 0.8% to 2% by weight when dried (2) (3). When the leaves are only used as a food additive/flavoring agent, you aren’t consuming too much eucalyptus oil at a given time.
If ingested in a large quantity, it is toxic and possibly lethal. Deaths have occurred with as little as 3.5 mL undiluted, as documented by Aromatherapy Science.
Poisoning and overdose symptoms from ingestion can include:
- Muscular weakness
- Shortness of breath
- Pain in the upper abdomen (epigastric)
- Bluish skin (cyanosis)
- Pupil constriction (miosis)
Even with external uses, since the eucalyptus plant hasn’t been studied for safety during pregnancy, it should be avoided during that time. The same applies to nursing mothers.
Given the toxicity of the undiluted oil, obviously it’s not kid safe. Keep out of reach of babies, toddlers, and children.
The lesson? You’re a human, not a koala. Let them eat it and enjoy the many external uses!
What is the difference between Eucalyptus radiata vs. Eucalyptus globulus? These two are the most popular varieties and both are native to Australia. However, there are distinct variations between the composition and smell of each species.
Also known as blue gum oil, this is the most popular version for making essential oils, which is understandable given that it has the strongest scent. If you know the scent of Vicks vapor rub, that’s similar to what E. globulus smells like; minty with a hint of honey. There are USDA certified organic versions of this one.
The scent comes from the high eucalyptol content (1,8 Cineole), which makes up to 60% or more of the Eucalyptus globulus chemical composition (4). There are 44 different compounds in total, but among the remaining portion, only three are above 1% in concentration; alpha-pinene (16.1%), aromadendren (3.7%), and o-cymen (2.4%) (5).
Black peppermint oil is another name for it. The big difference you will immediately notice is that radiata has a milder scent versus globulus. This is because its composition is different; limonene (68.5%), alpha-terpineol (8.6%), alpha-terpinyl acetate (6.1%), alpha-pinene (3.0%), terpinen-4-ol (1.6%) and beta-pinene (1.1%). The rest are all under 1% each. In total, there are 72 natural chemicals inside (5).
Even though its chemical profile is quite different, it still has the plant’s classic smell albeit milder, with hints of orange or lemon. You can also buy organic eucalyptus oil for radiata, but very few brands offer it.
Which is better?
The same study which evaluated their compositions found that E. globulus oil showed the best antioxidant activity, while E. radiata was the winner for antibacterial activity. So each type has its own advantages. You can’t say one is better than the other, as the answer will depend on the use of it.
In total, there are over 700 different types of eucalyptus trees. Only 9 of those are non-Australian. Just 15 to 20 species are used commercially (6). We discussed the two most common species and aside from those, here are a few others you might come across:
- Eucalyptus citriodora – When you see a label that says lemon eucalyptus oil, this is what you’re getting. It contains over 50% citronellal, which is best known for its ability to repel mosquitoes (7).
- Eucalyptus dives – Known as blue peppermint tree or broad-leaved peppermint eucalyptus oil. If properly diluted, this is one of the least irritating on the skin, but it is among the worst irritants of the lungs. That’s due to it’s high alpha-phellandrene and piperitone content. Those with asthma and sensitive sinuses should probably avoid E. dives.
- Eucalyptus polybractea – It’s called blue mallee oil and because it doesn’t have much aldehyde, it’s one of the best species for those with sensitive lungs. It has more cineol than any other species; up to 91% (8).
- Eucalyptus smithii – Commonly known as the gully gum tree, its scent is more woody and mellow versus E. globulus. Because it is one of the mildest, its expectorant quality works great in steam baths, showers, saunas, and other scenarios where less is more.
So those are the common types, but what are they good for?
Without further ado, here is how to use eucalyptus oil today, as well the research for unproven things which might become possible uses in the future.
Eucalyptus oil benefits
1. Natural mosquito repellent
This one isn’t just some far-fetched home remedy, as there are major bug sprays on the market which use it (E. citriodora). At least one has gotten rave reviews by Consumer Reports.
Either as a stand-alone or in a blend, on PubMed there are studies which have tested lemon eucalyptus oil mosquito repellent in Ethiopia (9), Tanzania (10), and even against the Aedes mosquito, which is a tropical and subtropical species known for carrying the Zika virus and dengue fever (11).
Some of us here even put this DEET-free solution to the test, with the company of white rhinos in the middle of nowhere! You can see the results in our natural mosquito repellent reviews, which we tested in Zambia, Botswana, and South Africa.
2. May help asthma attacks
Given that they produce lots of pollen, you definitely can be allergic to eucalyptus. There are case studies of people who have had their asthma symptoms made worse by it (12). One asthmatic here at Superfoodly experiences severe asthma attacks whenever he is around the trees.
Then why do so many purport that eucalyptus essential oil helps their asthma and clears their lung?
For starters, 100% pure oil should only contain trace amounts of pollen. That’s quite different than the airborne pollen.
Secondly, there have been 2 double-blind and placebo-controlled trials whose results suggest that the 1.8-cineol (eucalyptol) might offer anti-inflammatory benefits in bronchial asthma (13).
That first trial only had 32 patients but the more recent trial was quite large – 247 asthmatic participated (14).
For 6 months straight, each person took an oral 200 mg cineole dosage (extracted from the leaves) or a placebo. Each was used 3x daily. It was said…
“…the patient group treated with cineole showed significantly more improvements to the multiple testing criteria than the patients in the placebo group”
3. Cough suppressant
If you look on the OTC drug label for Vick’s Vapor Rub, this what it says for the ingredients verbatim (15):
- Camphor (synthetic) 4.8% (cough suppressant and topical analgesic)
- Eucalyptus oil 1.2% (cough suppressant)
- Menthol 2.6% (cough suppressant and topical analgesic)
When sick with a cold, many people do claim it helps them breathe easier. Sniffing eucalyptus oil directly can be dangerous given how strong it is. Rubbing a couple drops on the chest or using it in a diffuser is safer method.
Even though Procter & Gamble classifies eucalyptus oil for cough on their product, to be clear it has not been recognized as a medicine by the government for that purpose.
4. May lessen COPD symptoms
Given the last two uses, it’s no surprise scientists are also looking at its effect on people with chronic obstructive pulmonary disease (COPD).
In a double-blind and placebo controlled trial, 242 COPD patients received the same eucalyptus oil dosage as the asthmatics; 200 mg of cineole extracted from it, or a placebo, taken 3x daily for 6 months (16). Their conclusion claimed:
“These collective findings underline that cineole not only reduces exacerbation rate but also provides clinical benefits as manifested by improved airflow obstruction, reduced severity of dyspnea and improvement of health status”
The side effects seen in the cineole group were not considered “clinically relevant nor statistically significant.” Only 3 of the people getting cineole were determined to have side effects caused by the eucalyptus extract and those were nausea, heartburn, and diarrhea.
5. Improves stuffy nose and allergies
Whether it’s the lung-related trials, or someone using oil for colds by breathing it in, what is the mechanism that might be responsible for those alleviating symptoms?
Evidence suggests it may be the 1.8-cineole. That’s the compound that eucalyptus globulus oil has in a 60% concentration. A German scientist laid his theory as to how it works (17):
“…strong evidence that 1,8-cineole controls inflammatory processes and mediator production of infection- or inflammation-induced mucus hypersecretion by its action as anti-inflammatory modifier…”
In other words, asthma, COPD, and sinusitis are quite different diseases, but they all share a similar trait – during attacks, there can be too much mucus lining the airway surfaces.
In 2015, a German otolaryngology department used living slices of human nasal turbinates. Those are structures inside the nose which can swell up and block airflow. They studied in the lab what cineole would do to them (18).
“Treatment of rhinosinusitis, COPD or bronchial asthma strongly requires the reduction of mucus overproduction, a hallmark of inflammatory airway diseases. For the first time our findings demonstrate a 1,8-cineol-dependent reduction of mucus-production and expression of the NF-kB target gene MUC2…”
They’re proposing that cineole reduces mucus production by affecting some of the genes which control it.
6. Makes hair look healthier
There are countless shampoos, conditioners, and other products which make use of it as an ingredient. The presumption among consumers – or at least us – is that they are doing so because of the pleasant scent.
It may be beneficial in other ways, too.
Long term tests using using eucalyptus oil on the scalp were carried out on Japanese and Caucasians, both women and men (42). The following physical parameters were found to be improved after usage:
- hair gloss intensity
- bending stress at the root
These weren’t just subjective opinions, either. For elasticity, they used the nano-indentation method of atomic force microscopy (AFM) to compare the hair against the placebo-treated side.
When it comes to beards, that benefit seems to be a myth. There are websites talking about how to use eucalyptus oil for hair growth, but no science exists on that.
Nor are there studies to suggest it can make your beard grow faster.
7. Skin antifungal
The essential oil of the species E. pauciflora, known as snow gum or white sallee, was found to have “strong antifungal activity” at even low doses (1 microl/ml) when it was tested in the lab against several types of fungi found in skin infections (19).
After those tests, they formulated an ointment with a 1% concentration of the oil and gave it to 50 patients who had the following types of fungus infections; Tinea pedis (athlete’s foot), Tinea corporis (ringworm), Tinea cruris (jock itch).
After treatment, it was claimed that 60% had complete recovery and 40% had significant improvement.
Other lab research has observed “physical damage and morphological alterations” to certain types of skin fungus species when they were exposed to E. smithii essential oil (20).
8. Candida yeast infections
While this plant has been tested on a plethora of different fungal species, this one deserve special attention. It’s a normal species found on and in humans, but for some people its growth gets out of control.
Candidiasis can happen in the mouth and throat (oral thrush), in the vagina (yeast infection), and most serious of all – invasive candidiasis – which is when it’s in the bloodstream (21). This disease tends to affect women more than men and for some of them, candida overgrowth in the gut becomes only a managed disease, rather than one that can be permanently cured.
The effectiveness of the prescription disinfectant chlorhexidine was compared in the lab to Eucalyptus globulus essential oil (22). It was reported that both had…
“…the same antimicrobial activity for the following gram-negative bacteria: Escherichia coli and Proteus vulgaris, and the fungus Candida albicans.”
Research using other species, like E. robusta and E. saligna, have also reported Candida albicans colonies being inhibited by the oils (23).
9. Kills head lice
Any parent knows this parasite is big problem for toddlers and young children. Worse yet, these lice are becoming more resistant to conventional treatments and there is public concern over the neurotoxins used in some medications used to treat it.
Which purported herbal remedy is better for this, eucalyptus oil vs. tea tree oil?
In 2017, a Victoria, Australia based pharmaceutical company published a trial which pitted the oil of Eucalyptus smithii against piperonyl butoxide, a popular medication for lice (24). The specific brand was Pfizer’s Banlice mousse, which they say “was chosen as the neurotoxic comparator for this study as it is a market leader in Australia.”
After the infected scalps of the boys and girls were treated, the essential oils were…
“…found to be more than twice as effective in curing head lice infestation as P/PB mousse [Pfizer Banlice] in per-protocol participants (Trial 1; 83% vs 36%)”
However this was more than just using eucalyptus oil for lice prevention or treatment. The solution contained an 11% concentration of E. smithii and a 1% concentration of another essential, Leptospermum petersonii (lemon scented tea tree). So this isn’t a good analysis of how each type might kill or prevent these parasitic insects on their own.
10. Protects pets from fleas
Speaking of tiny insects, the order of Siphonaptera comprises over 2,500 different species of fleas found throughout the world. Sometimes, you find them on your dog or cat.
Is eucalyptus safe for dogs? That depends on its use. The essential oil is poisonous to dogs if ingested. ASPCA reports that salivating, vomiting, diarrhea and other side effects can result from the eucalyptol and other oils in the plant. They report its toxic for dogs, cats, and horses (25).
Since ASPCA doesn’t provide details, it’s possible they may be thinking only eating/drinking it, while ignoring purely topical applications like flea spray. Whatever the case, to play it safe, it would be best to avoid using eucalyptus essential oil on dogs and cats in any way.
But there may be another way this plant can help fight fleas.
A number of home remedy and gardening sites report that by having a tree in your hard, the aroma repels fleas and ticks.
Now this strategy hasn’t specifically been researched for fleas (Siphonaptera). Though considering the success seen with other types of insects, there is a reasonable amount of evidence to suggest this might work.
The good news is these trees grow like a weed, so it won’t take long for them to mature.
The bad news is that you need to live in a growing zone 7 to 11 and that rules out the northern parts of the US. Being water hogs, they won’t be legal in parts of California.
11. Deters bed bugs
Home remedy blogs say it can help with these, but can it?
Just like with dog fleas, the tiny little Cimex lectularius (common bed bug) has not been specifically tested using this type of oil.
However, a couple years ago researchers at Rutgers tested natural bed bug sprays made with essential oils (26). Some contained this plant. The results were disappointing; 7 out of the 10 did not even manage to kill 50% of bed bugs when they were directly sprayed!
Those taller bars on the left are traditional chemical treatments, EcoRaider and Temprid SC. They did well, the natural products not so much.
If you have realistic expectations and know what you’re getting yourself into, then it doesn’t look like these natural versions hurt. If they help, it might just not be much.
Using eucalyptus oil with laundry in a washing machine, as a rinse or detergent additive, is unlikely to be sufficient for killing active manifestations. Though perhaps it might help repel them from setting up shop in the first place, by spraying it directly onto your mattress, bed sheets, and comforter.
Published in the prestigious JAMA medical journal, a couple authors screen the medical databases and came up with 53 articles related to bed bugs (27). Upon reviewing all of them, one of the conclusions they made was this:
“Prevention of bed bug bites is best achieved with avoidance, because no repellents for the insects have been demonstrated conclusively to be effective. The mosquito repellant, oil of lemon eucalyptus, may help.”
On a related note, using it for roaches or as a repellent for mice and rats has not been tested.
12. Eliminates dust mites
Even if the oil doesn’t work for bed bugs, there may be another good reason to wash your clothes and bedding in it.
Does eucalyptus oil kill dust mites?
As long as two decades ago, research was being published about the advantages of washing with it, for controlling dust mites (28).
During this decade, there was a study about the benefits of using it on soft toys (e.g. stuffed animals) which are a magnet for these insects.
Using a total of 36 toys, scientists froze them, tumble dried them on high heat, and washed them with this essential oil. You would think the first two would do a better job at killing the mites, but that wasn’t the case (29):
- 95.1% average reduction with freezing
- 89.1% with hot tumble drying
- 95.1% from washing with eucalyptus
They suggested any one of these methods – or using multiple – would be viable strategies for babies’ and toddlers’ toys.
“These three HDM [house dust mite] elimination techniques give parents of infants effective and acceptable methods of limiting HDM exposure.”
13. Antiviral properties
First off, let’s shoot down the dangerous notion of using eucalyptus oil against herpes. Aside from not being an approved treatment for that (or any other viral infection) the fact is that some bloggers are misconstruing a study about herpes simplex virus I (HSV1).
It was a mouse study which did make use of eucalyptus and peppermint oil, but not as a treatment. No, it was using them as “permeation enhancers” as part of a topical treatment of acyclovir (the prescription Valtrex) (37). Eucalyptus for cold sores or genital herpes has not been studied in animals or humans.
“…only moderate antiviral effects were revealed by essential oils and monoterpenes when these drugs were added to host cells prior to infection or after entry of HSV into cells. However, both essential oils and monoterpenes exhibited high anti-HSV-1 activity by direct inactivation of free virus particles.”
But remember, what happens in a Petri dish may completely different than a living body. Regardless, it’s an interesting preliminary finding.
When Italians tested E. globulus against the mumps virus, only “mild activity” was observed (40).
During an experiment at a Tunisian university, there were eight different types of eucalyptus oils (41):
- E. bicostata
- E. cinerea
- E. maidenii
- E. odorata
- E. sideroxylon
- E. astringens
- E. lahmannii
- E. leucoxylon
Most of these are quite obscure, but they chose them because they grow locally throughout Tunisia, by way of introduction from Australia.
E. odorato showed the best activity against bacteria, while E. bicostata had the best antiviral characteristics. The results however were far from impressive.
Some spammy sites are peddling the eucalyptus oil cold remedy; the idea that it can help prevent or treat the common cold or influenza.
Those are both caused by viruses and neither have been tested for it in any capacity. Sure, breathing the vapors in might offer temporary relief of cold congestion in the nose, but there’s no science that says it can do anything to kill the cold or flu virus.
Overall, the antiviral benefits appear to be weak. Though given how little testing there is for any particular virus, it’s too early to judge one way or another.
14. Antibacterial properties
In 2017, a French lab study found that a blends of the essential oils Ceylon cinnamon, Queen Anne’s lace (Daucus carota), rosemary and eucalyptus (E. globulus) were effective against 14 different bacterial strains tested, including some which were resistant to antibiotics (30). But that was a blend.
Is eucalyptus essential oil antibacterial?
The bacteria Porphyromonas gingivalis is a culprit in some periodontal diseases as well as GI and respiratory tract infections.
Researchers in India tested several EOs against it in the lab and found that this one performed the best, followed by tea tree, chamomile, and turmeric oils (31).
Another study used a film coated with eucalyptus and tea tree oil (32). They reported:
“Strong bactericidal activity was observed with very low minimum bactericidal concentration (MBC) values on both E. coli and S. aureus.”
How about bacteria in fish? Seven different types were obtained from farmed flounder and tested using E. globulus (33). Antimicrobial activity was seen for every type.
Another lab test used globulus against Staphylococcus aureus, which is the cause of staph infections in humans and animals (34):
A = control (bacteria without treatment)
B = 0% (film without oil)
C = 1% oil
D = 3% oil
E = 5% oil
As you see, the 5% dosage of eucalyptus nanoemulsion and chitosan solution (chelating agent) seemed to work well:
“…no viable cells were observed after 24-hour treatments with 5%.”
It has also demonstrated antibacterial activity against food borne pathogens (35).
The University of Illinois identified a total of 32 “anti-tuberculosis active compounds” in E. citriodora oil; different types of monoterpenes and sesquiterpenoids (36). While its major component was weak (18% inhibition), some were said to show greater than 90% efficacy against airborne tuberculosis.
That’s just a sampling about some of the more recent antimicrobial studies involving this plant extrac. Though to be clear, natural antibiotics like this have not been tested in humans and they should not be used as medicine.
Reviews of eucalyptus oil for acne you may come across online. Know that tests for the Propionibacterium acnes bacteria don’t exist in published medical literature. While P. acnes isn’t the root cause of zits, it does make them more inflamed. That’s why antibiotics are so often prescribed as an acne treatment.
15. Soothes sore feet
Vaseline, vegetable shortening, vinegar and Vicks VapoRub have been called “the four V’s” for foot care (43). Feet clearly are not the intended uses of these, so why do so many people use them?
One reason may be toenail fungus. In a pilot study of 18 people who topically treated their toes with Vicks VapoRub, 15 of them experienced a positive effect in their onychomycosis fungal infection of the nail beds (44).
But Vick’s contains other ingredients. Is there anything to suggest this plant oil alone can help with that or other foot ailments?
When raw paws were tested with 1,8-cineole (the main compound in E. globulus), it actually caused oedema. That’s swelling and a buildup of fluid (45). Obviously if it does that, eucalyptus essential oil is not good for you!
Though what happens when you look at the entire oil, not just the isolated 1,8-cineole?
Without human testing, no one can claim rubbing eucalyptus oil on the feet – or soaking them in a diluted solution – is going to offer proven benefits. Though it definitely offers aromatherapy and perhaps that is a good enough reason to continue the age old tradition of use as a foot soak.
16. Joint and knee pain relief
It’s been touted as being among the best essential oils for rheumatoid arthritis. Is that just another marketing scam?
Maybe, but maybe not.
A South Korean university conducted a randomized clinical trial of 52 patients who had gotten a total knee replacement and were then treated with aromatherapy (48).
- 25 were given eucalyptus diluted to a 3% dosage, using 97% almond oil.
- 27 were given 100% almond oil, as a placebo.
- The oils were dabbed on a gauze and placed under the patients’ nose for 30 minutes, beginning on the 3rd day after the operation and continuing for 3 consecutive days.
Knee pain according to a visual analog scale (VAS), heart rate, blood pressure, and other parameters were tracked before and after these aromatherapy sessions.
The following charts show the differences…
The white bars are the control (100% almond) and the black are for eucalyptus.
In addition to lower pain scores, there was noticeably lower blood pressure (systolic) and heart rate, both of which suggest less stress.
A similar study was done with arthritis patients and the aromatherapy was said to have “major effects on decreasing pain and depression levels” (49). However that one used rosemary and eucalyptus oil along with others blended together, so it’s doesn’t suggest anything about one particular type.
Now there are oil roll-ons, rubbing creams, and other products for sale which claim to help sore muscles and joint pain. If these work, they haven’t been clinically validated.
Last but not least, we come to the benefit of just smelling good. Its oldest purpose!
What’s new about aromatherapy is that now, you have research suggesting other medicinal uses might result from it. Are they proven? Nope. But at least the possibilities are all beneficial things and nothing bad.
There are many uses for eucalyptus oil around the house:
- Use in room diffusers
- Buy shower sprays which contain it
- Dilute in shampoo or conditioner bottle
- Add 1 tsp to bathwater
- Rub on chest or neck
- Add 1 tbsp to final rinse of laundry
- Drink eucalyptus leaf tea
In place of a diffuser, the poor man’s version of putting eucalyptus oil in a humidifier can work too. You can achieve the ideal 1% concentration by simply diluting 4 teaspoons in a half gallon of water. Over time though, using a humidifier will cost you more.
Where can I buy it near me?
Walmart, CVS, and other big box retailers don’t carry it. Stores that sell it include Whole Foods and some health/nutrition shops.
Unfortunately there is not a good substitute for eucalyptus oil. Yes, there are some others which share similar compounds like helichrysum. It contains 1,8-cineole like E. globulus and a-pinene like E. radiate, but the concentrations are exponentially lower. Another thing that’s exponentially different is the price of pure helichrysum… typically 5 to 10x more expensive because so few use it. Not a good alternative!
Even if you find it for sale locally, that doesn’t mean you should get it. We checked at Whole Foods in Los Angeles and they had 5 different brands in stock…
3 were made in China (Aura Cacia, Vitality Works, Wyndmere), 1 had an unmarked country of origin (Whole Foods 365 brand), and only 1 was definitely not from China (Aura Cacia organic was made in Australia).
Australian eucalyptus oil sources include the following brands: Eureka, Euky Bear spray, Goanna, Jones Formula, Kelly’s World Famous, and Queensland Company. Eagle brand is made in Singapore.
All of those are primarily sold outside the US. Which can you buy here?
The big names like Young Living and Eden’s Garden can have different countries of origin, depending on the type. Check the label and while it’s no guarantee of being non-Chinese, it does seem that many of the organic eucalyptus oils come from Australia or New Zealand and sometimes India.
If you want our recommendations, here are a couple on Amazon we like:
E. globulus – Try Plant Therapy’s USDA certified organic
E. radiata – Try Plant Therapy’s from Australia. It’s NOT organic, but no reputable brands sell organic for this species.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.