Researchers in Czechoslovakia reported in the 1950s that cannabis extracts killed bacteria. In 2008, Italian and British chemists confirmed this in laboratory tests. The plant’s active compounds, the cannabinoids, strongly killed MRSA. MRSA is a staph bacterium that many standard antibiotics cannot kill. Since 2008 the idea has been tested in mice and in early human trials. Eighteen years after 2008, no cannabinoid antibiotic has been approved anywhere. This article explains each step of the research and the specific reasons why it has not yet produced a medicine.
Read this first. Everything below is laboratory research and early-stage trials. Nothing here is a treatment for any infection. No cannabinoid is licensed as an antibacterial anywhere in the world. A bacterial infection needs a doctor’s diagnosis and the right antibiotic. In Thailand, cannabis flower is a controlled herb. It may be dispensed only on a PT 33 prescription.
Two terms to know before you start
MRSA and antibiotic-resistant bacteria
Staphylococcus aureus (“staph”) is a common bacterium. Some healthy people carry it in their nose without being ill. It can also infect skin, wounds and deeper tissue.
MRSA stands for methicillin-resistant Staphylococcus aureus. These strains resist a whole class of antibiotics, the class that methicillin belongs to. Methicillin is a penicillin-type (beta-lactam) antibiotic, and MRSA resists nearly all antibiotics of this class. This makes resistant bacteria hard to treat. The first antibiotic a doctor chooses may fail, and fewer drugs remain that still work. MRSA can cause serious and occasionally life-threatening infections, and it remains a major cause of drug-resistant infection worldwide.
This is why the cannabis results drew attention. A compound that kills MRSA in a different way from existing antibiotics would not be blocked by MRSA’s resistance.
Gram-positive and Gram-negative bacteria
Microbiologists sort most bacteria into two groups with a colour test called the Gram stain. Gram-positive bacteria have a thick cell wall and no outer membrane. Gram-negative bacteria have a thinner wall plus an extra outer membrane, and that membrane keeps many substances out. As a result, many compounds that kill Gram-positive bacteria fail against Gram-negative ones.
Here are the bacteria from this article in each group:
| Group | Bacteria named in this article |
|---|---|
| Gram-positive | Staphylococcus aureus (including MRSA), Streptococcus pneumoniae, Clostridioides difficile |
| Gram-negative | Escherichia coli (E. coli), Pseudomonas, Neisseria gonorrhoeae, N. meningitidis, Moraxella catarrhalis, Legionella pneumophila |
The cannabinoid results follow this pattern, as section 3 shows. Whenever a post or a label says something “kills bacteria”, ask which bacteria and in what kind of test.
1. The first research: Olomouc, Czechoslovakia, 1950s
This research started in Olomouc, a university city in what is now the Czech Republic. There, three researchers, Jan Kabelík, Zdeněk Krejčí and František Šantavý, screened more than 3,000 plant species for substances that kill bacteria. Cannabis was one of the plants that showed up in that screen.
They published their first results in the Czech medical journal Lékařské listy in 1952. More results appeared in a 1955 conference volume from the university in Olomouc and in the German journal Die Pharmazie (1957–1959). In 1960 they summarised the work in English in the United Nations journal Bulletin on Narcotics. That paper describes how they isolated the antibacterial substances, their bacteriological experiments and what they saw when treating patients.
Later work also looked at viruses. In 1980, Blevins and Dumic published a paper in the Journal of General Virology. They reported that THC (tetrahydrocannabinol, the main intoxicating cannabinoid) stopped herpes simplex virus types 1 and 2 from multiplying in cell culture. Cell culture means human or animal cells grown in a lab dish. Later studies of THC against herpes viruses did not all agree with this result.
What to do with this: when someone quotes “old studies”, check the year and the type of test: lab dish, animals or people. The 1950s work was mainly lab work and treatment reports. Section 3 covers the modern studies.
2. The 2008 confirmation
In 2008, a team of Italian and British researchers published a study in the Journal of Natural Products. Appendino and Gibbons were the first and second authors (full reference at the end). They tested five major cannabinoids against several MRSA strains in the lab.
All five showed strong activity against MRSA, even though these strains resist conventional antibiotics. The authors said the activity was so strong that it pointed to a specific way of killing the bacteria. They did not identify what it was. Later work (section 3) suggests the cannabinoids act mainly on the bacterial cell membrane, the outer skin of the cell.
This explains the interest. MRSA is defined by its resistance to a whole class of drugs. A compound that kills it in a way that resistance does not cover would be more than just another antibiotic. It could be a new type of treatment.
The idea of a cannabis cream came from news coverage, not from the paper itself. In September 2008, news reports quoted the researchers as saying cannabis-based creams could be developed for skin infections that do not heal. Appendino told MIT Technology Review that the most practical use would be to apply cannabinoids to the skin, on ulcers and wounds.
What to do with this: if you read “cannabis cream kills MRSA”, remember where it came from. It was a news report about a lab study, not a tested product.
3. 2008 to 2026: from the lab dish to mice and early human trials
There is still no licensed cannabinoid antibacterial. However, the idea has not been ignored. Since 2008 it has been tested in animals and in early human trials. “Early” means small trials designed to check safety and whether there is any effect at all.
- McMaster University (Canada), 2020. Farha and colleagues published in ACS Infectious Diseases. They tested 18 cannabinoids against MRSA. Cannabigerol (CBG), a non-intoxicating cannabinoid, worked best. It also worked against biofilms and against “persister” cells. A biofilm is a slimy layer that bacteria build to protect themselves. Persister cells are dormant bacteria that survive antibiotics. CBG appears to act on the bacterial membrane. It cleared infection in mice infected with MRSA. The authors noted a problem: CBG is also toxic to the body’s own cells. The range of doses that is useful but not harmful may therefore be narrow.
- University of Queensland (Australia), 2021. Blaskovich and colleagues published in Communications Biology. They used synthetic CBD (cannabidiol, the main non-intoxicating cannabinoid, made in a lab rather than extracted from plants). It was active against more than 20 types of Gram-positive bacteria, including MRSA, Streptococcus pneumoniae and Clostridioides difficile. It also killed a small group of Gram-negative bacteria. These were Neisseria gonorrhoeae (the cause of gonorrhoea), N. meningitidis, Moraxella catarrhalis and Legionella pneumophila. It did not kill most Gram-negatives, such as E. coli or Pseudomonas.
- In mice with skin infections, a 5% CBD preparation applied to the skin reduced bacterial numbers more than an inactive base did. However, it was less effective than the standard 2% mupirocin ointment, an antibiotic ointment commonly used for skin infections.
- Given by mouth or by injection, CBD did not work against a deep MRSA infection. The authors called this lack of whole-body effect CBD’s biggest weakness.
- BTX 1801, Botanix (synthetic CBD, applied inside the nose). Botanix Pharmaceuticals is a small Australian pharmaceutical company. In February 2021 it reported a Phase 2a study. Phase 2a is an early, small trial in people. The study was randomised, double-blind and vehicle-controlled. In plain words: volunteers were assigned by chance, and neither they nor the researchers knew who received the product. The comparison group received the same base with no CBD.
- The volunteers were healthy people who carried S. aureus in their nose.
- The company said its ointment and gel were safe and well tolerated. It reported that they cleared the bacteria in up to about three-quarters of participants by day 7. The effect had largely faded by day 28.
- These results were reported by the company itself.
- The US Food and Drug Administration (FDA) gave the programme Qualified Infectious Disease Product status. This is a US designation for drugs being developed against serious infections. It gives an extra five years of US market exclusivity and makes the drug eligible for faster FDA review.
- A Phase 2b study in haemodialysis patients was planned. These are patients whose blood is filtered by a machine because their kidneys have failed. No published results of that study could be found.
- BTX 1503, Botanix (synthetic CBD applied to the skin, for acne). A Phase 2 trial in 368 patients with moderate-to-severe acne reported results in October 2019. Its registration number is NCT03573518 on the US trial registry ClinicalTrials.gov. It did not meet its primary endpoint. The primary endpoint is the main result a trial is designed to measure, which here was fewer inflamed spots at 12 weeks. Acne involves bacteria, inflammation and oil production together. So this was not a pure test of antibacterial effect.
To sum up the current state: the idea of applying cannabinoids to the skin or inside the nose has been tested in early trials. The results were mixed, and there is still no licensed product. That gap has specific causes, not a cover-up. They are listed below.
Why there is still no product: five concrete reasons
1. Realistically, it only works on the surface of the body. It is hard to reach bacteria-killing concentrations inside the body. CBD also binds heavily to proteins in the blood. Blaskovich’s group named this as the likely reason CBD failed when given by mouth or injection. The same gap between “works in a dish” and “works in the bloodstream” comes up in the cancer topic. For an antibiotic that must work through the bloodstream, this is a serious obstacle. On the skin or inside the nose, the dose is applied directly where the bacteria are. That is exactly where the trials have gone.
2. Making a usable preparation is hard. Cannabinoids dissolve easily in fats and oils but hardly at all in water. A medicine needs a stable, effective concentration that reaches the right depth of skin. It also has to stay effective while it sits in storage. This is a real pharmaceutical problem.
3. Safe dose versus harmful dose. The CBG work showed that damaging bacterial membranes can also damage human cells. The range of doses that is both effective and safe may be narrow.
4. Resistance will come eventually. Early studies found that bacteria did not easily become resistant to cannabinoids. But bacteria eventually adapt to every drug. A new way of killing them delays resistance; it does not prevent it.
5. Antibiotics earn little money. This is the biggest obstacle and the least discussed. New antibiotics are used sparingly, for short courses, and are often held in reserve for when other drugs fail. They earn far less than a drug taken daily for life. That is why many major pharmaceutical companies have left antibiotic development. The cannabinoid projects above were run by university groups and one small company. Most new antibacterials now develop this way: slowly, and often never reaching approval.
What to do with this: when a post claims cannabis “cures infections but is suppressed”, check it against these five reasons. They explain the gap without any conspiracy.
4. What it would take to become a real medicine
Most of the pieces already exist. There is a use on the skin or in the nose, defined synthetic preparations and early human data. The expensive part is missing. That means larger controlled trials that show a clinical benefit in patients, followed by approval from a medicines regulator.
The most likely targets are still the ones already chosen:
- Skin infections that do not heal.
- Clearing S. aureus from the nose in high-risk patients.
In both cases the medicine goes on the surface, so the problem with blood levels does not apply. MRSA is also a real problem in both settings.
If this succeeds, the result will be a licensed pharmaceutical product containing one defined cannabinoid at a fixed concentration. Doctors will prescribe it for a named condition. It will not be cannabis, and nobody will be able to make it at home. The epilepsy topic shows what this path looks like when a cannabinoid medicine actually completes it.
What to do with this: any cannabis product sold today with an antibacterial claim is not this medicine. No such product has been approved.
5. Practical warning: skin infections and homemade preparations
This section matters more than the science.
See a doctor about a skin infection that is not getting better. Cellulitis (infection spreading under the skin), abscesses (pockets of pus) and infected wounds get worse without treatment. MRSA in particular can cause serious, occasionally life-threatening infection. Antibiotics work best when started early.
Do not put an unregulated cannabis preparation on broken skin. Unregulated cannabis has a documented risk of contamination with moulds and bacteria. Putting it into an open wound adds germs instead of removing them. Ask questions about homemade balms in the topical cannabis topic.
A result in a lab dish does not mean the product works on skin. In a dish, the compound touches the bacteria directly. On a patient it must pass through skin, pus, biofilm and blood proteins and reach the right depth. The 2021 mouse study shows this. CBD on the skin helped, but less than the standard antibiotic ointment.
Translator’s note: Thailand’s climate raises this risk. Rainy-season humidity encourages mould on drying flower. Flower or oil kept at 30–35 °C goes off faster, especially when power cuts stop air conditioning. A homemade balm can carry this contamination straight into a wound. For mould on cannabis flower and the toxins it can leave behind, see Mycotoxins on Cannabis Flower. If a wound is red, hot, swelling or leaking pus, go to a hospital or clinic. Tell the doctor about anything you have already applied.
6. The lesson from history
Cannabis was listed in Western pharmacopoeias, the official medicine reference books, for about a century. It was used for a very wide range of conditions. Almost none of those uses were tested to modern standards.
Some of those uses were probably real, and the antibacterial effect may be one of them. The 2008 study and the work since then suggest the lab activity is genuine. The real loss of that period was this: cannabis was used for many conditions but properly studied for none. So when it was banned, there was no evidence to defend it with, only tradition.
Today this line of research is clearer than before. It has been tested in early trials, and there is still no licensed product. What holds it back is pharmacology and money, not a conspiracy. That is a more accurate complaint than “suppression”.
What to do with this: when you share a claim about a medical use, also share the type of evidence: lab dish, animals, early trial or approved medicine. Why Personal Testimony Is Not Medical Evidence explains how to judge the weaker kinds.
7. In Thailand
Cannabis flower is a controlled herb under the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568. It was issued under the Thai Traditional Medicine Protection Act B.E. 2542 (1999) and has been in force since 26 June 2025.
- Flower may be sold only with a PT 33 (ภ.ท.33) prescription from an authorised practitioner.
- Each prescription covers no more than 30 days.
- Advertising and online sale of flower are prohibited.
There is no approved antibacterial use for cannabis in Thailand or anywhere else.
Translator’s note for growers and licence holders: this research gives growers no new market yet. The trials used synthetic CBD, not plant extract. What you can do now is practical:
- Do not make or repeat antibacterial claims for flower or flower products. Advertising flower is banned. See what you can and cannot post before you write about health effects.
- Do not process or sell home preparations from flower without the right licence. Under the 1999 Act, research, sale or processing of a controlled herb needs a licence (Section 46). Doing it without one carries up to 1 year in prison and/or a fine of up to 20,000 baht (Section 78).
- Know the extract rules if a research group contacts you. Under the Ministerial Regulation on Cannabis or Hemp Extracts B.E. 2569, in force since 26 April 2026, licences for extracts above 0.2% THC go only to three kinds of applicant. They are Thai juristic persons that are not “foreign” under the Foreign Business Act B.E. 2542, state agencies and the Thai Red Cross Society. Licence criteria for flower were also tightened by the Ministerial Regulation on Controlled Herbs (No. 2) B.E. 2569, in force since 30 April 2026.
- Keep your flower clean and tested. The contamination risk in section 5 is the same risk a buyer or researcher will test for. Learn to read a lab report in How to Read a Cannabis Certificate of Analysis.
The draft Cannabis Control Act is not law yet. The Cabinet approved the draft on 22 September 2026 and sent it to the House of Representatives.
Discuss below
Two questions are still open. Is any group in Southeast Asia working on cannabinoid antibacterials for the skin or nose? Have the early trials led to new results? This region grows cannabis and also has a serious MRSA problem, so it could reasonably do this research. If you work in microbiology or dermatology, or know of published regional work, post the reference below this topic.
This is general educational information, not medical advice. A suspected infection needs a medical assessment and the right antibiotic.
References
- Kabelík J, Krejčí Z, Šantavý F. First results in Lékařské listy, 1952; further results in a 1955 Olomouc university conference volume and in Die Pharmazie, 1957–1959.
- Kabelík J, Krejčí Z, Šantavý F. “Cannabis as a medicament.” Bulletin on Narcotics 1960; 12(3): 5–23 (United Nations Office on Drugs and Crime).
- Blevins RD, Dumic MP. Journal of General Virology 1980; 49: 427–431 (THC and herpes simplex virus types 1 and 2 in cell culture).
- Appendino G, Gibbons S, et al. “Antibacterial cannabinoids from Cannabis sativa: a structure–activity study.” Journal of Natural Products 2008; 71(8): 1427–1430.
- News coverage, September 2008, including MIT Technology Review (researchers on cannabis-based creams for persistent skin infections, ulcers and wounds).
- Farha MA, et al. ACS Infectious Diseases 2020 (McMaster University; 18 cannabinoids against MRSA; CBG).
- Blaskovich MAT, et al. Communications Biology 2021 (University of Queensland; synthetic CBD against Gram-positive and selected Gram-negative bacteria; mouse skin and systemic infection models).
- Botanix. BTX 1801 Phase 2a nasal study of S. aureus carriage, company-reported results, February 2021.
- Botanix. BTX 1503 Phase 2 acne trial, NCT03573518, results reported October 2019.