Vemlidy (Tenofovir Alafenamide)
Antiviral medication for chronic hepatitis B virus infection
Quick Facts About Vemlidy
Key Takeaways About Vemlidy
- Treats chronic hepatitis B: Vemlidy suppresses HBV replication but does not cure hepatitis B; treatment is usually long-term
- Improved safety profile: Compared to older tenofovir (TDF), Vemlidy has significantly less impact on kidney function and bone mineral density
- Never stop without medical advice: Abruptly discontinuing Vemlidy can cause severe hepatitis flares that may be life-threatening in patients with advanced liver disease
- Does not prevent transmission: You can still transmit HBV to others through sexual contact or blood exposure while on treatment
- Take with food daily: One 25 mg tablet once daily with food ensures optimal drug absorption and blood levels
What Is Vemlidy and What Is It Used For?
Vemlidy (tenofovir alafenamide) is a prescription antiviral medicine that treats chronic hepatitis B virus (HBV) infection by preventing the virus from reproducing. It is approved for adults and children aged 6 years and older weighing at least 25 kg.
Vemlidy contains the active substance tenofovir alafenamide (TAF), which belongs to a class of antiviral medications known as nucleotide reverse transcriptase inhibitors (NtRTIs). These drugs work by interfering with a key enzyme that the hepatitis B virus needs to replicate its DNA inside liver cells (hepatocytes). By blocking this enzyme, Vemlidy prevents the virus from multiplying, which helps reduce the viral load in the blood and allows the liver to heal.
Hepatitis B is a viral infection that attacks the liver and can cause both acute and chronic disease. Chronic hepatitis B, defined as infection lasting more than six months, affects an estimated 296 million people worldwide according to the World Health Organization (WHO). Without treatment, chronic HBV can lead to serious complications including liver cirrhosis, liver failure, and hepatocellular carcinoma (liver cancer). Vemlidy helps control the infection and reduce the risk of these complications.
It is important to understand that Vemlidy does not cure hepatitis B. The medication controls the infection by suppressing viral replication, and treatment is typically continued long-term, often for many years. Your doctor will determine the appropriate duration of treatment based on your individual clinical response and laboratory results, including HBV DNA levels, liver enzyme tests (ALT), and hepatitis B surface antigen (HBsAg) status.
How Is Vemlidy Different from Older Tenofovir Formulations?
Vemlidy (TAF) is a newer prodrug of tenofovir that was specifically designed to address some safety concerns associated with the older formulation, tenofovir disoproxil fumarate (TDF). TAF has greater plasma stability, which means it can be administered at a much lower dose (25 mg versus 300 mg of TDF) while still achieving higher concentrations of the active drug inside liver cells where it is needed most.
The key clinical advantage of TAF over TDF is a significantly reduced systemic exposure to tenofovir, resulting in approximately 90% lower tenofovir levels in the blood. This translates into improved safety profiles for the kidneys and bones. Clinical studies have demonstrated that patients switching from TDF to TAF experienced improvements in bone mineral density and markers of kidney function, making Vemlidy particularly suitable for patients who may be at risk of renal or skeletal complications.
Vemlidy controls hepatitis B infection but does not eliminate the virus. Even while on treatment, you can still transmit HBV to others. Continue to practice safe behaviors, including using barrier protection during sexual contact and avoiding sharing needles or personal items that may have blood on them.
What Should You Know Before Taking Vemlidy?
Do not take Vemlidy if you are allergic to tenofovir alafenamide or any of its other ingredients. Before starting treatment, inform your doctor about any liver disease, kidney problems, co-infections with hepatitis C or D, or HIV status. Pregnant or breastfeeding women should consult their doctor before use.
Contraindications
You must not take Vemlidy if you have a known allergy (hypersensitivity) to tenofovir alafenamide or any of the other ingredients in the tablet, which include lactose monohydrate, microcrystalline cellulose, croscarmellose sodium, and magnesium stearate. If you experience signs of an allergic reaction such as swelling of the face, lips, tongue, or throat (angioedema), hives, or difficulty breathing, stop taking Vemlidy immediately and seek medical attention.
Additionally, Vemlidy should not be taken together with other medications that contain tenofovir alafenamide, tenofovir disoproxil, or adefovir dipivoxil, as combining these could increase the risk of side effects without additional clinical benefit.
Warnings and Precautions
Several important warnings apply when taking Vemlidy. Discuss the following with your doctor before starting treatment:
- Liver disease: Patients with liver disease who are being treated with antiviral medications for hepatitis B have a higher risk of severe and potentially life-threatening liver complications. Your doctor may need to perform regular blood tests to monitor your liver function throughout treatment.
- Kidney disease: If you have existing kidney problems or if tests have shown impaired kidney function, tell your doctor before starting Vemlidy. Blood and urine tests to monitor kidney function may be ordered before and during treatment.
- Co-infection with hepatitis C or D: Vemlidy has not been studied in patients who have both hepatitis C or D and hepatitis B. If you have multiple viral hepatitis infections, your doctor will need to plan treatment accordingly.
- HIV status: If you are unsure whether you have HIV, your doctor should offer you an HIV test before you start Vemlidy. Using Vemlidy alone in a patient with undiagnosed HIV could lead to HIV drug resistance.
Stopping Vemlidy suddenly can cause your hepatitis B to worsen significantly (hepatic flare). In patients with advanced liver disease or cirrhosis, this can be life-threatening. If you stop treatment, your doctor will need to monitor you closely with regular health checks and blood tests for several months to watch for signs of worsening infection.
Pregnancy and Breastfeeding
If you are pregnant, think you may be pregnant, or are planning to become pregnant, consult your doctor before taking Vemlidy. Your doctor will weigh the benefits and risks of treatment during pregnancy. Clinical data on the use of tenofovir alafenamide during pregnancy is limited, and your healthcare provider will make an individualized decision based on the severity of your hepatitis B infection.
Breastfeeding is not recommended during treatment with Vemlidy. Tenofovir alafenamide and its metabolite tenofovir are excreted in breast milk, and the potential effects on a breastfed infant have not been adequately studied. Additionally, hepatitis B virus itself can be transmitted through breast milk if the infant is not adequately protected through vaccination and hepatitis B immunoglobulin.
Use in Children and Adolescents
Vemlidy is approved for use in children aged 6 years and older who weigh at least 25 kg. The medication has not been studied in children younger than 6 years or those weighing less than 25 kg, and should not be given to these patients.
Decreases in bone mineral density have been reported in some children treated with Vemlidy. The long-term effects on bone health and future fracture risk in pediatric patients remain uncertain. Your doctor will monitor bone health during treatment and discuss any concerns about skeletal development. Report any bone pain or fractures to your healthcare provider promptly.
Vemlidy tablets contain lactose monohydrate. If you have been told by your doctor that you have an intolerance to certain sugars, contact your doctor before taking this medicine. The tablets contain less than 1 mmol (23 mg) sodium per tablet, meaning they are essentially sodium-free.
How Does Vemlidy Interact with Other Drugs?
Vemlidy can interact with several important medications including rifampicin, certain HIV antivirals (ritonavir, darunavir), antiepileptic drugs (carbamazepine, phenytoin), and St. John's Wort. Never combine Vemlidy with other products containing tenofovir or adefovir. Always inform your doctor about all medications you are taking.
Drug interactions can change how Vemlidy works or increase the risk of side effects. Tenofovir alafenamide is a substrate of P-glycoprotein (P-gp), and drugs that strongly affect P-gp activity can alter the blood levels of Vemlidy. It is essential to tell your doctor or pharmacist about all medications you are currently taking, have recently taken, or might take in the future, including herbal products and over-the-counter medicines.
Medications That Must Not Be Combined with Vemlidy
You must not take Vemlidy together with other medications that contain any of the following active substances, as this could lead to increased side effects or reduced efficacy:
- Tenofovir alafenamide (found in several HIV combination products)
- Tenofovir disoproxil (found in older HIV and HBV treatments)
- Adefovir dipivoxil (an older hepatitis B treatment)
Major Interactions
| Drug / Drug Class | Type of Interaction | Clinical Effect | Recommendation |
|---|---|---|---|
| Rifampicin, Rifabutin, Rifapentin | P-gp induction | Significantly decreased TAF levels; reduced antiviral efficacy | Avoid co-administration; discuss alternatives with your doctor |
| Carbamazepine, Phenobarbital, Phenytoin, Oxcarbazepine | Enzyme induction / P-gp induction | Decreased TAF levels; potential treatment failure | Avoid co-administration; consider alternative antiepileptic drugs |
| St. John's Wort (Hypericum perforatum) | P-gp induction | Decreased TAF levels; risk of virological failure | Do not use with Vemlidy |
| Ritonavir- or cobicistat-boosted HIV regimens (darunavir, lopinavir, atazanavir) | P-gp inhibition | Increased TAF levels; potential for increased side effects | Use with caution; dose adjustment may be needed; consult your doctor |
| Ketoconazole, Itraconazole | P-gp inhibition | Increased TAF levels | Monitor for side effects; consult your doctor |
This table does not list all possible interactions. Always consult your doctor or pharmacist before starting any new medication, including over-the-counter drugs and supplements, while you are taking Vemlidy. Bring a complete list of your current medications to every medical appointment.
What Is the Correct Dosage of Vemlidy?
The recommended dose of Vemlidy is one 25 mg tablet taken once daily with food. Treatment duration is typically long-term (at least 6-12 months, often years). Always take Vemlidy exactly as your doctor has told you.
Always take Vemlidy exactly as your doctor has prescribed. Do not change the dose or stop treatment without consulting your doctor first. Taking Vemlidy with food is important to ensure the correct level of active substance is absorbed into your body.
Adults
Standard Adult Dose
25 mg (one tablet) once daily with food. The tablet should be swallowed whole. Treatment is usually continued for at least 6-12 months but may extend to several years depending on clinical response. Your doctor will regularly assess the need for continued treatment based on your HBV DNA levels, ALT values, and HBsAg status.
Children (6 years and older, weighing at least 25 kg)
Pediatric Dose
25 mg (one tablet) once daily with food. The same dose as adults applies to children aged 6 years and older who weigh at least 25 kg. Vemlidy should not be given to children under 6 years of age or those weighing less than 25 kg.
Elderly
Dose in Older Adults
No dose adjustment is required for elderly patients. However, as kidney function tends to decline with age, your doctor may monitor your renal function more closely during treatment. If significant kidney impairment is present, your doctor will decide whether Vemlidy remains appropriate for you.
Missed Dose
If you forget to take a dose of Vemlidy, what you should do depends on how much time has passed since your usual dosing time:
- Less than 18 hours since your usual time: Take the missed dose as soon as possible, then take the next dose at the normal time.
- More than 18 hours since your usual time: Skip the missed dose entirely. Wait and take the next dose at your regular time.
- Never take a double dose to make up for a forgotten tablet.
- If you vomit within 1 hour of taking Vemlidy, take another tablet. If you vomit more than 1 hour after taking it, you do not need to take another dose.
Consistency is essential for antiviral treatment. Try to take Vemlidy at the same time each day to maintain steady drug levels in your blood. Setting a daily alarm or using a pill organizer can help you remember your dose.
Overdose
If you accidentally take more than the recommended dose of Vemlidy, contact your doctor or go to the nearest emergency department immediately. Take the tablet bottle with you so you can clearly describe what you have taken. There is no specific antidote for tenofovir alafenamide overdose, and treatment is supportive. Tenofovir can be removed by hemodialysis.
If you stop taking Vemlidy, your hepatitis B may worsen. In patients with advanced liver disease or cirrhosis, stopping treatment can cause severe, potentially life-threatening hepatic flares. Even if you need to stop for any reason, your doctor must monitor you closely with regular blood tests for several months. Tell your doctor immediately if you notice new or unusual symptoms after stopping treatment, particularly symptoms you associate with hepatitis B such as fatigue, jaundice (yellowing of skin or eyes), dark urine, or abdominal pain.
What Are the Side Effects of Vemlidy?
The most common side effect is headache (affects more than 1 in 10 people). Common side effects include diarrhea, nausea, vomiting, dizziness, abdominal pain, joint pain, rash, itching, bloating, flatulence, and fatigue. Uncommon but serious side effects include angioedema and urticaria.
Like all medicines, Vemlidy can cause side effects, although not everybody gets them. Most side effects are mild to moderate in severity and tend to resolve on their own as your body adjusts to the medication. However, some side effects may require medical attention. Tell your doctor if any side effects become severe or persistent.
Very Common
May affect more than 1 in 10 people
- Headache
Common
May affect up to 1 in 10 people
- Diarrhea
- Vomiting
- Nausea
- Dizziness
- Abdominal pain
- Joint pain (arthralgia)
- Rash
- Itching (pruritus)
- Bloating
- Flatulence (gas)
- Fatigue
Uncommon
May affect up to 1 in 100 people
- Swelling of the face, lips, tongue, or throat (angioedema)
- Hives (urticaria)
Laboratory Abnormalities
Detected through blood tests
- Elevated liver enzyme (ALT) levels
- Increases in fasting lipid levels
- Increases in fasting blood glucose
During HBV treatment, body weight may increase, and fasting levels of lipids (cholesterol, triglycerides) and/or glucose in the blood may also rise. Your doctor will perform regular blood tests to monitor for these metabolic changes. If you notice significant weight gain, discuss this with your healthcare provider.
Long-Term Safety Considerations
While Vemlidy has a better kidney and bone safety profile compared to tenofovir disoproxil fumarate, there is still a potential risk of kidney problems with long-term use. Your doctor will monitor your kidney function through blood and urine tests at regular intervals during treatment. Signs of kidney problems may include changes in urine output, swelling in the legs or ankles, or persistent fatigue. Report any such symptoms to your doctor promptly.
Bone mineral density decreases have been observed in some patients, particularly in pediatric populations. If you develop bone pain or experience a fracture during treatment, inform your doctor as they may wish to perform additional bone density assessments.
Reporting suspected adverse reactions after authorization of the medicine is important for ongoing safety monitoring. Healthcare professionals and patients are encouraged to report any suspected side effects through their national adverse reaction reporting system, such as the FDA MedWatch program in the US, the Yellow Card scheme in the UK, or the EMA EudraVigilance system in the EU.
How Should You Store Vemlidy?
Store Vemlidy in its original container at room temperature, away from moisture. Keep the desiccant inside the bottle. Keep out of reach of children. Do not use after the expiration date printed on the bottle and carton.
Proper storage of Vemlidy is important to ensure the medication remains effective throughout its shelf life. Follow these guidelines:
- Keep out of the sight and reach of children.
- Store in the original packaging to protect from moisture. Vemlidy is sensitive to humidity, so keep the bottle tightly closed at all times.
- Do not remove the silica gel desiccant from the bottle. The desiccant protects the tablets from moisture damage. Do not swallow the desiccant.
- Check the expiration date before taking each dose. The expiration date refers to the last day of the indicated month. Do not use Vemlidy after this date.
- Do not dispose of medicines in wastewater or household waste. Ask your pharmacist how to dispose of medicines you no longer use. These measures help protect the environment.
Vemlidy tablets are supplied in bottles of 30 tablets. Outer cartons may contain 1 bottle (30 tablets) or 3 bottles (90 tablets). Not all pack sizes may be marketed in your country.
What Does Vemlidy Contain?
Each Vemlidy tablet contains tenofovir alafenamide fumarate equivalent to 25 mg tenofovir alafenamide. The tablets are yellow, round, film-coated, and marked with "GSI" on one side and "25" on the other.
The active substance is tenofovir alafenamide. Each film-coated Vemlidy tablet contains tenofovir alafenamide fumarate, equivalent to 25 mg of tenofovir alafenamide.
Inactive Ingredients
The other ingredients in Vemlidy serve various functions in the tablet formulation:
| Component | Ingredient | Function |
|---|---|---|
| Tablet core | Lactose monohydrate | Filler / diluent |
| Tablet core | Microcrystalline cellulose (E460(i)) | Binder / filler |
| Tablet core | Croscarmellose sodium (E468) | Disintegrant |
| Tablet core | Magnesium stearate (E470b) | Lubricant |
| Film coating | Polyvinyl alcohol (E1203) | Film-forming agent |
| Film coating | Titanium dioxide (E171) | Opacifier / colorant |
| Film coating | Macrogol (E1521) | Plasticizer |
| Film coating | Talc (E553b) | Anti-adherent |
| Film coating | Yellow iron oxide (E172) | Colorant |
Tablet Appearance
Vemlidy tablets are yellow, round, film-coated tablets marked with "GSI" on one side and "25" on the other side. They are supplied in bottles of 30 tablets containing a silica gel desiccant that must remain in the bottle to protect the tablets from moisture. The desiccant is in a separate sachet or container and must not be swallowed.
Frequently Asked Questions About Vemlidy
Vemlidy (tenofovir alafenamide) is used to treat chronic hepatitis B virus (HBV) infection in adults and children aged 6 years and older who weigh at least 25 kg. It works by preventing the hepatitis B virus from reproducing in the body, which helps control the infection and prevent liver damage. Vemlidy does not cure hepatitis B but helps manage the disease when taken as prescribed.
Vemlidy (tenofovir alafenamide, TAF) is a newer, more targeted formulation of tenofovir. While both TAF and TDF deliver the same active drug (tenofovir) to liver cells, TAF achieves this at a much lower dose (25 mg vs. 300 mg) with 90% less tenofovir exposure in the bloodstream. This significantly reduces the risk of kidney and bone side effects while maintaining comparable antiviral efficacy. Patients who are at risk of kidney or bone problems may benefit from TAF over TDF.
No, you should never stop taking Vemlidy without first consulting your doctor. Abruptly discontinuing treatment can cause a severe hepatitis B flare, where the virus rapidly multiplies and causes significant liver inflammation. In patients with advanced liver disease or cirrhosis, this can be life-threatening. If treatment needs to be stopped for any reason, your doctor will plan a careful monitoring strategy with regular blood tests over several months.
The most common side effect of Vemlidy is headache, which affects more than 1 in 10 people. Other common side effects (affecting up to 1 in 10 people) include diarrhea, nausea, vomiting, dizziness, abdominal pain, joint pain (arthralgia), rash, itching, bloating, flatulence, and fatigue. Most side effects are mild and tend to improve as your body adjusts to the medication. Contact your doctor if any side effects become severe or persistent.
No, Vemlidy does not cure hepatitis B. It suppresses the virus by preventing it from reproducing in the body, which helps control the infection and prevents liver damage. Treatment with Vemlidy is typically long-term and may continue for many years. Your doctor will regularly monitor your blood tests to assess the effectiveness of treatment and determine whether continued therapy is needed.
Yes, Vemlidy is approved for children aged 6 years and older who weigh at least 25 kg. The dose is the same as for adults: one 25 mg tablet once daily with food. Vemlidy has not been studied in children younger than 6 years or those weighing less than 25 kg. Doctors should monitor bone mineral density in pediatric patients as decreases have been reported during treatment.
References
- European Medicines Agency (EMA). Vemlidy (tenofovir alafenamide) - Summary of Product Characteristics. Last updated 2025. Available at: ema.europa.eu/en/medicines/human/EPAR/vemlidy
- U.S. Food and Drug Administration (FDA). Vemlidy (tenofovir alafenamide) - Prescribing Information. Gilead Sciences, Inc. Reference ID: 4906721.
- European Association for the Study of the Liver (EASL). EASL 2017 Clinical Practice Guidelines on the management of hepatitis B virus infection. Journal of Hepatology. 2017;67(2):370-398. doi:10.1016/j.jhep.2017.03.021
- Terrault NA, Lok ASF, McMahon BJ, et al. Update on prevention, diagnosis, and treatment of chronic hepatitis B: AASLD 2018 hepatitis B guidance. Hepatology. 2018;67(4):1560-1599. doi:10.1002/hep.29800
- World Health Organization (WHO). Guidelines for the prevention, diagnosis, care and treatment for people with chronic hepatitis B infection. Geneva: World Health Organization; 2024.
- Chan HLY, Fung S, Seto WK, et al. Tenofovir alafenamide versus tenofovir disoproxil fumarate for the treatment of HBeAg-positive chronic hepatitis B virus infection: a randomised, double-blind, phase 3, non-inferiority trial. The Lancet Gastroenterology & Hepatology. 2016;1(3):185-195. doi:10.1016/S2468-1253(16)30024-3
- Buti M, Gane E, Seto WK, et al. Tenofovir alafenamide versus tenofovir disoproxil fumarate for the treatment of patients with HBeAg-negative chronic hepatitis B virus infection: a randomised, double-blind, phase 3, non-inferiority trial. The Lancet Gastroenterology & Hepatology. 2016;1(3):196-206. doi:10.1016/S2468-1253(16)30107-8
- Agarwal K, Brunetto M, Seto WK, et al. 96 weeks treatment of tenofovir alafenamide vs. tenofovir disoproxil fumarate for hepatitis B virus infection. Journal of Hepatology. 2018;68(4):672-681. doi:10.1016/j.jhep.2017.11.039
About the Medical Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, consisting of licensed physicians specializing in hepatology, infectious diseases, and clinical pharmacology. All content follows international medical guidelines (WHO, EMA, FDA, EASL, AASLD) and the GRADE evidence framework.
Medical Writing
iMedic Medical Editorial Team
Specialists in hepatology and infectious diseases
Medical Review
iMedic Medical Review Board
Independent review following GRADE evidence framework
Evidence standard: Level 1A - Based on systematic reviews and randomized controlled trials. Content follows EMA SmPC, FDA prescribing information, and international clinical practice guidelines (EASL, AASLD, WHO).
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