Cannabis articles about hepatitis C usually cite one study from 2006. It found that patients who used cannabis were more likely to finish interferon treatment, an older and very harsh hepatitis C therapy. Interferon has now been almost completely replaced. Modern hepatitis C tablets cure more than 95% of patients, usually in 12 to 24 weeks, with few side effects.
This article covers what the hepatitis C and HIV studies actually found. It separates the findings that still matter in Thailand in 2026 from those that belong to an older era of treatment. Each section ends with something you can do.
This is general information, not medical advice. Do not change your HIV medicines or delay hepatitis C treatment because of anything you read here. Both conditions have very effective treatments, and the outcome depends on taking them as prescribed. In Thailand, cannabis flower is a controlled herb. It may be sold only with a PT 33 (ภ.ท.33) prescription.
1. Hepatitis C: A Real Finding About an Old Treatment
The 2006 study
Dr Diana Sylvestre of the University of California, San Francisco (USA) led the study. Her team followed 71 people at a clinic in Northern California. All of them were recovering from substance use. All were treated with interferon (an injected drug) and ribavirin (an antiviral medicine taken with it).
The results appeared in the European Journal of Gastroenterology and Hepatology in October 2006. Of the 71 patients, 22 used cannabis. These 22 were more likely to stay on treatment for at least 80% of the planned course (95% against 67%).
More of the cannabis users also reached a sustained virological response (SVR), which in practice means a cure. The figures were 54% of cannabis users against 18% of non-users. Anyone who checks the paper will find this as its main result.
The authors linked the benefit to adherence, meaning that patients kept to their treatment schedule. Cannabis may have helped them cope with a very hard regimen. The study did not show any antiviral effect: nothing in it suggests that cannabis acted on the virus itself.
How to read the result
The study had real limits:
- It was small. With only 71 patients, the researchers could not fully adjust for other differences between cannabis users and non-users.
- It was observational. The researchers recorded what patients chose to do. They did not assign cannabis to anyone.
- Cannabis use was self-reported. Patients said whether they used it, and nobody measured it.
The higher cure rate comes from more patients finishing treatment. It does not come from any effect of cannabis on the virus.
What changed after 2006
Interferon treatment meant months of injections. Common side effects were flu-like symptoms, fatigue, insomnia, appetite loss, nausea, muscle and joint pain, and depression. Many patients stopped early, so anything that helped them finish mattered a great deal.
Treatment is different today. The World Health Organization (WHO) recommends pan-genotypic direct-acting antivirals (DAAs) for all adults and adolescents, and for children from age three. DAAs are tablets that act on the virus directly. “Pan-genotypic” means they work against all the genetic types (genotypes) of the hepatitis C virus.
The first treatments without interferon were approved in 2013–14. WHO says treatment usually lasts 12 to 24 weeks, depending on whether the person has cirrhosis (severe scarring of the liver). Side effects are few, and DAAs cure more than 95% of people with hepatitis C.
Generic versions have brought the price down sharply. In 2021, WHO said low- and middle-income countries could aim to pay as little as US$60 for a 12-week course of generic sofosbuvir with daclatasvir. The prices countries actually pay still vary widely. In Thailand, published reports say sofosbuvir/velpatasvir was added to the Universal Coverage benefit package in 2021.
WHO’s latest estimates are for the year 2024 and appear in the Global Hepatitis Report 2026:
- about 47 million people were living with chronic hepatitis C;
- about 0.9 million new infections occur each year;
- about 240,000 people died, mostly from cirrhosis and liver cancer.
The 2006 finding is therefore history from the interferon era. It is not a reason to use cannabis for hepatitis C today. The side effects it helped patients put up with have largely gone. In 2026, the priority for anyone with hepatitis C is a diagnosis and access to DAAs, because DAAs cure the infection.
What to do: If you have hepatitis C, or you are unsure whether you have it, ask a public hospital about testing. Also ask whether you are currently eligible for DAA treatment. Eligibility rules can change, and the tablets cure the infection.
Does cannabis harm the liver in hepatitis C?
Most of the research asks this question. The concern is fibrosis, which is scarring of the liver that can progress to cirrhosis.
Early studies linked daily cannabis use to faster fibrosis. Those studies were cross-sectional, meaning they looked at people at a single moment. A study like that cannot show which came first, the cannabis use or the liver damage.
A stronger prospective study followed the same people forward over time. Kelly and colleagues published it in Clinical Infectious Diseases in 2016. They followed 575 women living with both HIV and hepatitis C for a median of 11 years. The women were taking part in the Women’s Interagency HIV Study, a long-term research study of women with HIV.
In that study, cannabis use was not linked to progression to significant fibrosis. Alcohol was linked to it. This reassures on one narrow point only. It does not make cannabis a treatment for hepatitis.
What to do: Tell your liver doctor honestly how much alcohol you drink and whether you use cannabis. In this study, alcohol was the habit linked to liver scarring. Honest answers help your doctor plan liver checks that match your real risks.
Hepatitis B is a different disease
Chronic hepatitis B is common across Thailand and Southeast Asia. The cure described above does not apply to it. No current medicine can cure chronic hepatitis B.
Hepatitis B is controlled instead with long-term antiviral medicines such as tenofovir or entecavir, plus regular screening for liver cancer. No cannabis product can replace either of these.
What to do: If you have chronic hepatitis B, keep taking your antiviral medicine. Keep every liver-cancer screening appointment as well. Screening is how liver cancer is found early.
One warning that still applies: drug interactions
Some DAAs are affected by interactions involving liver enzymes or transporters. Transporters are proteins that move drugs into and out of cells. Cannabinoids also interact with the cytochrome P450 enzymes, a group of liver enzymes that break down many medicines.
What to do: Before you start DAA treatment, tell the treating team about everything else you take. Include cannabis flower, oils, edibles and herbal products. They can then check whether any of these could change the level of your hepatitis C medicine.
2. HIV: Stronger Evidence, for Symptoms Only
The HIV evidence looks better than the hepatitis C evidence, for two reasons. First, the studies tested relief of symptoms, not effects on the virus. Second, the trials were properly controlled, although they were small.
Nerve pain
HIV-associated sensory neuropathy is nerve damage linked to HIV. It is common and painful, and existing drugs often do not help much.
Abrams and colleagues, at the University of California, San Francisco and San Francisco General Hospital (USA), reported a trial in Neurology in 2007. It was randomised and placebo-controlled. Patients were assigned by chance to cannabis or to a placebo (an inactive comparison). It ran for 5 days with patients staying in hospital, and 50 patients completed it.
Patients smoked cannabis three times a day. Their daily pain fell by a median of 34%, against 17% with placebo. The researchers concluded that patients coped well with the side effects of smoked cannabis and that it relieved this pain. They found the effect comparable to oral drugs used for chronic nerve pain.
Ellis and colleagues, at the University of California, San Diego (USA), reported a crossover trial in Neuropsychopharmacology in 2009. In a crossover trial, each patient receives both cannabis and placebo at different times, so each person is compared with themselves. Twenty-eight patients completed it. Smoked cannabis reduced pain more than placebo when added to the pain medicines patients were already taking at a steady dose.
In the Ellis trial, cannabis was explicitly an add-on. It went to patients whose pain was not controlled by their usual treatment. The chronic pain evidence frames cannabis the same way.
This makes nerve pain one of the better-supported uses of cannabis. Both trials were small and short, however. The evidence is promising but not settled.
What to do: If you have HIV-related nerve pain, talk to your doctor about cannabis as an addition to your current pain treatment. Do not use it as a replacement. These trials only tested cannabis added to existing treatment.
Appetite and weight
The US National Academies of Sciences, Engineering and Medicine (NASEM) is a scientific advisory body. In 2017 it reviewed the research on cannabis. It found limited evidence that cannabis and oral cannabinoids increase appetite and reduce weight loss linked to HIV/AIDS.
“Limited” is a specific grade of evidence, not a dismissal. It is still well below the grades the same review gave elsewhere:
- “substantial” for chronic pain in adults;
- “conclusive” for oral cannabinoids against nausea and vomiting caused by chemotherapy.
Loss of appetite (anorexia) and severe weight and muscle loss from illness (cachexia) are different problems. See the forum topic on appetite loss and cachexia.
Dronabinol is a synthetic (lab-made) form of THC. In the United States it was first approved in 1985 for nausea and vomiting caused by chemotherapy. In 1992 its approval was extended to AIDS-related loss of appetite with weight loss.
Both dates came before effective HIV treatment arrived in 1996. At that time, AIDS wasting was common and often fatal. Dronabinol was approved to help appetite, and it does nothing to the virus. The patients in that evidence were very different from people living with HIV today.
What to do: If loss of appetite or weight is a problem for you, raise it with your HIV team. Tell them the evidence for cannabinoids here is graded only “limited”. That helps them weigh cannabinoids fairly against other options.
3. Antiretroviral Therapy: Why Taking It Every Day Matters
Antiretroviral therapy (ART) is the set of medicines that keeps HIV under control. Effective ART arrived in 1996. It changed HIV from a fatal illness into a long-term condition that can be managed.
ART keeps the virus suppressed only while you keep taking it as prescribed. That is why adherence, kept up over decades, is what decides the outcome in HIV. WHO guidance notes that missed doses are a common cause of treatment failure. Poor adherence can leave the virus unsuppressed and lead to drug resistance.
Anything that helps a person keep taking ART is useful. Anything that makes them miss doses is dangerous, whatever other benefit it brings. Observational studies of cannabis and ART adherence have found effects in both directions. Your HIV doctor therefore needs to know about your cannabis use, so they can watch for its effect on your adherence.
The older case for cannabis in HIV was about AIDS wasting and about patented medicines most patients could not afford. That was a real fight over access to medicines. It was a question of fairness and price, however. It was never clinical evidence that cannabis treats HIV.
Interactions with HIV medicines
Dronabinol is broken down mainly by two liver enzymes, CYP2C9 and CYP3A4. Both belong to the cytochrome P450 group. The THC and CBD in other cannabis products are also processed by this group.
Several HIV medicines strongly affect these enzymes, especially CYP3A4. Some slow the enzymes down (inhibitors), and some speed them up (inducers). Adding cannabis or a cannabinoid can therefore change drug levels in the blood. In ART, those levels matter a great deal. See the forum topic on drug interactions for how these interactions work.
None of this is a reason to hide cannabis use from your HIV doctor. It is the reason to tell them.
What to do: Write a list of every product you take, including cannabis flower, oils and edibles. Show it to both your HIV doctor and your pharmacist. Ask directly whether anyone has checked it for interactions with your ART. The check can show whether your HIV medicine levels might change.
4. Reading Personal Stories Carefully
Personal stories about cannabis and HIV are shared widely. In them, people living with HIV say cannabis brought back their appetite and weight. Some say it let them “reduce their reliance on medication”.
These stories can matter a lot to the people telling them. They have the same limits as any personal account, however. See why personal testimony is not medical evidence. The biggest limit is this: the person was almost always taking ART at the same time, so the effect of cannabis cannot be separated from the effect of ART.
The phrase “reduce reliance on medication” needs extra care. In HIV, the medicine is not a burden to cut down. It is the treatment that keeps the virus suppressed.
What to do: When you read or share an HIV story on the forum, check whether the person was also taking ART. Never repeat advice to cut down or stop ART. If a post gives that advice, reply with a link to this topic.
5. Summary of the Evidence
| Use | What the evidence shows |
|---|---|
| Nerve pain linked to HIV | Two small randomised trials showed benefit: 50 patients over 5 days, and 28 patients in a crossover trial. In the Ellis trial cannabis was explicitly an add-on to existing pain medicine. This is among the better evidence for cannabis. |
| Appetite and weight in HIV/AIDS | Limited evidence (NASEM 2017). This was the basis for dronabinol’s 1992 approval for AIDS-related appetite loss, before effective HIV treatment existed. |
| Staying on hepatitis C treatment | A 2006 observational study of interferon treatment: cannabis users more often finished treatment and were cured. Researchers credited better adherence. Interferon has largely been replaced by DAAs, which cure more than 95%, usually in 12–24 weeks. |
| Liver scarring with both HIV and hepatitis C | No link to cannabis in a prospective study of 575 women (Kelly 2016). Alcohol was linked. |
| Antiviral effect against HIV, hepatitis C or hepatitis B | None shown. The hepatitis C researchers linked their result to adherence, not to any effect on the virus. |
What to do: Use this table when someone online claims cannabis “treats” HIV or hepatitis. Point to the last row. None of these studies showed an antiviral effect.
6. The Rules in Thailand
Cannabis flower (ช่อดอกกัญชา) is a controlled herb under the Notification of the Ministry of Public Health Re: Controlled Herbs (Cannabis), B.E. 2568. The Notification was issued under the Thai Traditional Medicine Protection Act B.E. 2542 and came into force on 26 June 2025.
The main points are:
- Flower can be sold only with a PT 33 (ภ.ท.33) prescription from an authorised practitioner, for no more than 30 days per prescription.
- Advertising and online sale of flower are prohibited.
Health claims for products are regulated separately, according to the product category. The relevant laws are the Drug Act B.E. 2510, the Herbal Products Act B.E. 2562 and the Food Act B.E. 2522. Advertising any product as a treatment for HIV or hepatitis is therefore unsupported by evidence and also legally risky.
The Cannabis Control Act is still only a draft and is not law yet. The Cabinet approved the draft on 22 September 2026 and sent it to the House of Representatives. For the full legal picture, see advertising and selling rules for cannabis in Thailand and Thailand’s cannabis rules from 2022 to 2026.
Translator’s note: Many forum members grow cannabis or work in licensed shops. Customers living with HIV or hepatitis sometimes ask staff for advice. Do not suggest that any strain or product treats HIV or hepatitis, whether in a post, on a label or in a chat. Refer the person to their HIV or liver doctor and their pharmacist. That protects the patient and also protects your licence.
Translator’s note: The practical priorities in Thailand follow from the evidence above:
- HIV: Because of the interaction risk, your prescriber and pharmacist must be involved. This is not optional.
- Hepatitis C: Get access to DAA treatment, which cures it. Ask a public hospital about your current eligibility.
- Hepatitis B: You need long-term monitoring and treatment.
What to do before your next appointment: If you live with HIV and use cannabis or are thinking about it, bring your product list. Ask who checked it for interactions with your ART: the doctor or the pharmacist. This check is the most useful step in this whole article, and the one most often skipped.
If you have been through this in Thailand or elsewhere in the region, please share it below this topic. Say whether your interactions were actually checked and by whom. Leave out personal medical details you would not want to make public.
References
- Sylvestre DL, Clements BJ, Malibu Y. Cannabis use improves retention and virological outcomes in patients treated for hepatitis C. Eur J Gastroenterol Hepatol. 2006;18(10):1057–1063.
- Abrams DI, et al. Cannabis in painful HIV-associated sensory neuropathy: a randomized placebo-controlled trial. Neurology. 2007;68(7):515–521.
- Ellis RJ, et al. Smoked medicinal cannabis for neuropathic pain in HIV: a randomized, crossover clinical trial. Neuropsychopharmacology. 2009;34(3):672–680.
- Kelly EM, et al. Marijuana use is not associated with progression to advanced liver fibrosis in HIV/hepatitis C virus–coinfected women. Clin Infect Dis. 2016;63(4):512–518.
- National Academies of Sciences, Engineering, and Medicine. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. 2017.
- World Health Organization. Updated recommendations on HCV treatment, simplified service delivery and diagnostics. 2022.
- World Health Organization. Hepatitis C fact sheet (2026 update) and Global Hepatitis Report 2026.
- World Health Organization. News release on access to hepatitis C diagnostics and treatment in low- and middle-income countries, 27 January 2021.
- Dronabinol (Marinol) US prescribing information; “Dronabinol”, StatPearls, NCBI Bookshelf.
General information, not medical advice. Never reduce or interrupt antiretroviral therapy. Do not delay hepatitis C treatment: it is curable.