7 Biktarvy Side Effects Explained & How They May Impact You

Starting and staying on HIV treatment like Biktarvy is essential, not just to manage the virus but also to reduce the risk of transmission, long-term complications, and early death. However, success with HIV therapy also requires persistence, and one of the biggest barriers to sticking with treatment is how your body responds to it.

In a real-world study comparing Biktarvy with another HIV regimen, patients stayed on the alternative treatment for an average of 3.4 years, while those on Biktarvy remained for only 2.7 years. The main reason for stopping Biktarvy was side effects.

In this article, we’ll go over the possible side effects of Biktarvy and explain how they might affect you so you can feel more informed and supported in your treatment journey.

1. Gastrointestinal (GI) side effects

Digestive issues, especially nausea and diarrhea, are among the most commonly reported side effects of Biktarvy. In clinical trials, 6% experienced nausea, and another 6% reported diarrhea during early use.

Other GI symptoms observed in studies include:

• • Abdominal bloating or distention
  • Vomiting
  • Excessive gas (flatulence)
  • Indigestion (dyspepsia)
  • Abdominal pain

In a study, around 37% of participants developed GI symptoms within the first month of starting Biktarvy. Adults over age 45 had higher rates of discomfort, such as nausea, vomiting, stomach pain, and swallowing difficulties, compared to younger individuals. However, diarrhea occurred at similar rates across all age groups.

This trend may be due to how digestion changes with age. Slower stomach movement, reduced acid production, and shifts in gut bacteria can increase sensitivity to medications like Biktarvy. Additionally, underlying health conditions that are more common with age may worsen these symptoms.

People with gut microbiome imbalances (dysbiosis) should be more cautious with Gl side effects. HIV infection itself can damage gut tissues and disrupt the balance of bacteria, which may increase the risk of conditions like irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD).

In one published case, a 62-year-old man with HIV developed pancolitis, a severe form of ulcerative colitis (a type of IBD), after long-term use of Biktarvy. He experienced bloody diarrhea and abdominal pain. His stool sample had a calprotectin level of 1,159 µg/g, far above the normal level (under 50 µg/g), confirming severe inflammation in the colon.

If left unmanaged, ongoing digestive side effects can also lead to malabsorption, dehydration, and electrolyte imbalances.

2. CNS-related (Central Nervous System) side effects

In the first clinical trials of Biktarvy, very few people stopped taking it because of mental or nervous system side effects, only about 0% to 1%. The most common of these side effects, reported by at least 2% of users, were:

• • Headache – the most frequently reported (5%)
  • Fatigue
  • Vivid or unusual dreams
  • Dizziness
  • Insomnia

Fewer than 2% of people reported feeling depressed. Serious symptoms like suicidal thoughts or behavior happened in about 2%, mostly in those who already had a history of depression, past suicide attempts, or other mental health issues.

The same types of CNS side effects continued during the extended period of the study. However, three individuals experienced serious events, including seizure, suicide, and severe dizziness.

A separate real-world study observed similar side effects, though abnormal dreams were more common than headaches. In that study, symptoms began 13 days after starting Biktarvy. Less commonly reported neuropsychiatric effects included:

• • Amnesia
  • Fear or anxiety
  • Excessive drowsiness (somnolence)
  • Panic attacks
  • Cognitive difficulties
  • Paranoia
  • Reduced sexual desire (decreased libido)

Only a small number of people (1.4%) experienced mental health-related side effects serious enough to stop Biktarvy, consistent with findings from earlier clinical trials.

3. Weight Gain

Weight gain is one of the earliest metabolic changes that can happen when starting HIV treatment. While Biktarvy didn’t show significant weight gain in clinical trials, it has been reported in real-world use since it became widely available.

Most studies show that tenofovir alafenamide (TAF) and bictegravir (BIC) are the active ingredients in Biktarvy that are responsible for weight gain, with bictegravir being linked to the most weight gain.

In one study, people who took Biktarvy for 12 months gained an average of 3.6 lbs. Their BMI, levels of total cholesterol, LDL (“bad”) cholesterol, and blood sugar also increased.

Another study compared Biktarvy to a different HIV treatment. After 12 months, people on Biktarvy had:

• • A 1.23 kg/m² greater increase in BMI
  • An extra 2.84 kg of weight gain (around 6.3 lbs)
  • 76% more likely to gain 5% or more of your body weight
  • Twice as likely to gain 10% or more

This weight gain can increase your risk of heart disease or diabetes. In a Reddit discussion, one user shared that their cholesterol levels became very high after two years of taking Biktarvy. As a result, they were advised to either switch to Dovato or start taking statins to lower their levels.

Talk to your doctor about it when starting or switching HIV medications to find the safest option for you.

4. Sudden worsening of Hepatitis B

If you have both HIV-1 and hepatitis B (HBV) and stop taking Biktarvy, your hepatitis B can suddenly worsen (HBV flare). Your liver becomes inflamed, and ALT levels (a marker of liver damage) may rise to more than five times the normal limit.

Due to this serious risk, Biktarvy includes a black box warning to caution patients and healthcare providers.

In one reported case, a 53-year-old man with both HIV and chronic hepatitis B went to the emergency room after two days of nausea and pain in the upper right side of his abdomen. He hadn’t used alcohol or taken other medications like acetaminophen. He had stopped taking Biktarvy for several months, then restarted it three weeks before his symptoms began.

His vital signs were normal, but his liver was tender when touched. Blood tests showed very high liver enzymes.

The amount of HBV virus in his blood was very high, over 7 million copies per milliliter, although his HIV remained undetectable. Other possible causes, like hepatitis A or C, autoimmune disease, or genetic liver conditions, were ruled out.

Other studies show that around 20% to 25% may experience an HBV flare within the first 2 to 8 weeks of starting HIV treatment like Biktarvy. Of those, 1% to 5% may go on to develop symptoms of clinical hepatitis.

5. Immune reconstitution syndrome

When you start HIV treatment like Biktarvy, your immune system begins to recover. This recovery can sometimes be too aggressive, causing it to overreact to infections already in your body that weren’t causing problems before. This overreaction, called Immune Reconstitution Inflammatory Syndrome (IRIS), leads to inflammation.

IRIS occurs in up to 20% of people with HIV. In some cases, it can trigger hepatitis B (HBV) flare-ups.

A 24-year-old man who was diagnosed with HIV in 2018 came to a clinic after being off treatment for an unknown amount of time. His initial tests showed a high HIV viral load and evidence of chronic hepatitis but undetectable HBV viral load. He was then started on Biktarvy.

Three weeks later, he went to the ER with:

• • Joint pain
  • Diarrhea
  • Fatigue

His hepatitis B viral load had sharply increased to 295,304 copies/mL, confirming a new HBV flare-up. Other possible causes were ruled out.

His liver enzymes continued to rise but did not reach the threshold for liver failure. A liver biopsy later confirmed that the inflammation was caused by IRIS triggered by hepatitis B.

6. New or worsening kidney problems

Kidney problems have been reported in people taking TAF-containing products. Because Biktarvy contains TAF, it should also be used with caution. Reported cases include:

• • Acute Kidney Failure: When your kidneys can’t filter waste or balance fluids and electrolytes as they normally would. Symptoms might include:

• • • • Swelling in the legs or face
      • Fatigue
      • Nause
      • Trouble breathing

• • Proximal Tubulopathy: This means damage to a part of your kidney called the proximal tubule. This part normally helps your body take back nutrients, minerals, and fluids from your urine and return them to your blood. When it gets damaged, your body may lose important things like phosphate, sugar, and bicarbonate in your urine. This can lead to:

• • • • Muscle weakness
      • Bone problems
      • Imbalances in your blood chemistry

• • Fanconi Syndrome: This is a more severe form of proximal tubulopathy. It happens when your kidneys leak too many nutrients and minerals into the urine. Over time, Fanconi syndrome can cause:

• • • • Bone weakening (osteomalacia)
      • Dehydration
      • Muscle pain or weakness
      • Growth problems in children

In many of these cases, other health problems may have contributed to the kidney damage. It’s also possible that these conditions made people more likely to develop side effects from tenofovir (TAF).

7. Lactic acid buildup and enlarged fatty liver

Serious side effects like lactic acidosis and an enlarged fatty liver (sometimes fatal) have been reported in people taking nucleoside analogs, including emtricitabine (found in Biktarvy) and tenofovir disoproxil fumarate (TDF), either alone or with other HIV medications.

Lactic acidosis happens when too much lactic acid builds up in your blood. This can make your blood too acidic and can be dangerous if not treated quickly. You might feel:

• • Very tired or weak
  • Sick to your stomach or have stomach pain
  • Shortness of breath
  • Cold in your hands or feet
  • Like your heart is beating too fast or irregularly

One case involved a 67-year-old man with HIV on Biktarvy who came to the hospital with weakness and confusion. Tests showed severe lactic acidosis (pH 6.9, lactate 25 mmol/L). His condition improved with treatment, but lactic acid remained high. It was later discovered he had been taking Biktarvy twice daily instead of once. After stopping the medication, both kidney function and lactic acid levels improved.

In another case, a 36-year-old man with HIV/AIDS, hepatitis B, syphilis, and kidney disease was hospitalized with confusion and breathing issues. He improved with antibiotics and was restarted on Biktarvy. However, after just one dose, his lactate and creatinine levels spiked. Biktarvy was suspected and immediately stopped.

Noticed a Reaction?

If you experience unusual or serious side effects while taking Biktarvy, report them. Sharing this information helps the FDA monitor drug safety and identify rare or unexpected reactions that may not have been seen in clinical trials.

You can report side effects online at www.fda.gov/medwatch or by calling 1-800-FDA-1088. Your report could help improve safety information for others using the same treatment.

Wrap-up

Biktarvy can cause common side effects like nausea, diarrhea, and headaches. Older adults and people with existing gut issues may feel these more strongly. Some may also experience unusual dreams, fatigue, or dizziness.

Weight gain has been reported in real-life use, even though it wasn’t reported in clinical trials. This may raise the risk of heart problems or diabetes. If you also have hepatitis B, stopping Biktarvy suddenly can make your liver condition worse.

There’s also a chance of serious problems like kidney damage, lactic acid buildup, and fatty liver, especially in people with other health issues. Talk to your doctor if you notice any new or worsening symptoms while taking Biktarvy. Regular check-ups can help you manage side effects and stay safe during treatment.

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