What Happens If You Miss a Few Days of Biktarvy?

October 9, 2025 •

4 min read

To achieve and maintain viral suppression, an adherence rate of 95% or higher to antiretroviral therapy (ART) is often required [1.5.1]. So, what happens if you miss a few days of Biktarvy? Even a short break can allow the virus to replicate, increasing health risks [1.2.1].

Quick Summary

Missing doses of Biktarvy can lead to a rise in your HIV viral load (viral rebound) and create an opportunity for the virus to develop drug resistance, which may compromise future treatment options [1.3.2, 1.4.2].

Key Points

Viral Rebound: Missing a few days of Biktarvy can cause your HIV viral load to increase, as the drug levels in your blood fall [1.3.2].
Drug Resistance: The most significant risk of inconsistent dosing is the virus mutating, making Biktarvy and similar medications ineffective in the future [1.4.2].
Long Half-Life: Biktarvy has a long half-life, which provides some protection if you miss a single dose, but this buffer is not sufficient for multiple missed days [1.4.5].
Immediate Action Required: If you miss a dose, take it as soon as you remember unless it's almost time for the next one. Never take a double dose [1.7.1].
Consult Your Provider: Do not stop or alter your Biktarvy schedule without talking to your doctor. They can provide guidance if you miss multiple doses [1.2.1].
Adherence is Crucial: Maintaining at least 95% adherence is essential for long-term viral suppression and to prevent treatment failure [1.5.1].

Biktarvy is a highly effective single-tablet regimen used to treat HIV, combining three active ingredients: bictegravir, emtricitabine, and tenofovir alafenamide [1.2.2]. Its success hinges on consistent daily use to maintain a steady level of the medication in your body, which keeps the virus suppressed [1.2.3]. Missing doses can disrupt this balance, leading to serious consequences.

The Critical Importance of Adherence in HIV Treatment

Medication adherence in HIV care is the practice of taking your prescribed antiretroviral therapy (ART) exactly as directed. High levels of adherence are directly linked to better viral suppression, a stronger immune system, and reduced risk of transmitting the virus [1.5.2]. Studies show that adherence rates below 95% can lead to treatment failure and the development of drug-resistant HIV strains [1.5.1]. Inconsistent dosing allows the amount of HIV in the blood (viral load) to increase. This not only weakens the immune system but gives the virus a chance to mutate, potentially making your current medication ineffective [1.3.2].

Immediate and Long-Term Risks of Missing Doses

Viral Rebound

When you stop taking Biktarvy, even for a short time, the medication levels in your blood drop. This allows the HIV virus to begin making copies of itself again, leading to an increase in your viral load [1.2.1, 1.3.2]. A viral rebound can happen within a couple of weeks of stopping treatment [1.5.4]. While missing a single dose is unlikely to cause a significant issue due to the drug's long half-life, missing several consecutive days dramatically increases this risk [1.4.5, 1.2.8].

Development of Drug Resistance

The most significant long-term danger of missing doses is drug resistance [1.4.2]. When the viral load increases in the presence of low drug levels, the virus can mutate into new forms that are no longer affected by the medication [1.4.4, 1.4.6]. Resistance to the components in Biktarvy could mean that other similar antiretroviral drugs also become ineffective, limiting future treatment options [1.3.2]. This is why healthcare providers stress that you must not stop taking Biktarvy without their guidance [1.4.1].

Understanding Biktarvy's Pharmacology: Forgiveness and Half-Life

Biktarvy is considered a "forgiving" regimen to some extent because its components remain in the body for a significant period. The half-life of a drug is the time it takes for its concentration in the plasma to reduce by half.

Bictegravir: Has a plasma half-life of about 17.3 hours [1.6.3, 1.6.4].
Emtricitabine (FTC): Has an intracellular half-life of 39 hours [1.4.5].
Tenofovir Alafenamide (TAF): Has an intracellular half-life of 150 hours [1.4.5].

These long half-lives mean that drug levels remain high enough to suppress the virus for more than 24 hours, providing a buffer if you miss a single dose [1.2.8, 1.4.5]. However, this protective effect diminishes with each consecutive missed day. After about four days, the risk of viral rebound begins to increase significantly [1.2.7].

What to Do If You Miss a Dose

It is crucial to follow a clear plan if you miss a dose:

If you remember within 18 hours of your usual time, take the missed dose as soon as possible. Then, take your next dose at its regularly scheduled time [1.3.6, 1.7.5].
If more than 18 hours have passed, skip the missed dose entirely. Do not take the missed dose. Simply take your next dose at the usual time [1.3.6, 1.7.5].
Never double your dose to make up for a missed one. Taking two tablets at once can increase your risk of side effects [1.2.2, 1.7.3].
If you miss several doses, contact your healthcare provider for guidance. They can advise you on the next steps and may recommend a viral load test to ensure the medication is still working effectively [1.2.7].


Feature	Consistent Adherence (>95%)	Inconsistent Adherence (<95%)
Viral Load	Remains suppressed and undetectable [1.5.2].	Risk of viral rebound (increase in virus) [1.3.2].
Immune Function	CD4 count is maintained or improved.	Immune system can be damaged [1.3.2].
Drug Resistance	Very low risk of developing resistance [1.4.4].	High risk of the virus mutating and becoming resistant [1.4.2].
Treatment Options	Current regimen remains effective long-term [1.2.3].	Future treatment options may be limited [1.3.2].
Overall Health	Better health outcomes and quality of life [1.5.4].	Increased risk of HIV-related illnesses and progression to AIDS [1.5.1].

Tips for Preventing Missed Doses

Consistency is the cornerstone of successful HIV treatment. To avoid missing doses:

Set a daily alarm or use a medication reminder app on your phone [1.2.4, 1.7.1].
Incorporate taking your pill into a daily routine, such as at breakfast or bedtime [1.7.1].
Use a weekly pillbox to organize your medication [1.2.2].
Refill your prescription early to ensure you never run out of medication [1.2.1, 1.2.2].
Talk to your doctor or pharmacist if you are struggling with adherence. They can offer support and strategies to help [1.2.2].

Conclusion

Missing a few days of Biktarvy is a serious issue that can lead to viral rebound and the development of drug resistance, jeopardizing your long-term health and future treatment success. While the medication has a degree of forgiveness for a single missed dose, consistent daily use is non-negotiable for maintaining viral suppression. If you miss doses, it is essential to follow the correct procedure and, most importantly, communicate openly with your healthcare provider to ensure your treatment remains effective.

For more information on HIV treatment and adherence, you can visit HIVinfo.NIH.gov.

Frequently Asked Questions

If you remember within 18 hours of your usual time, take the dose right away and resume your normal schedule. If more than 18 hours have passed, skip the missed dose and just take your next one at the regular time. Do not double up [1.3.6, 1.7.5].

Missing 2-3 days increases the risk of your viral load rebounding (increasing) and gives the virus an opportunity to develop resistance. While Biktarvy is somewhat forgiving, repeatedly missing doses is dangerous. Contact your healthcare provider for advice [1.3.2, 1.2.8].

You might not feel sick immediately, but missing doses allows the virus to start replicating again, which can weaken your immune system over time and increase your risk of HIV-related illnesses [1.3.2].

It is highly unlikely that missing a single, isolated dose will cause drug resistance due to the medication's long half-life [1.2.8]. However, frequent or regular missed doses significantly increase this risk [1.4.2].

The components of Biktarvy have long half-lives. Bictegravir's plasma half-life is about 17.3 hours, while the intracellular half-lives of emtricitabine and tenofovir alafenamide are 39 and 150 hours, respectively. This helps cover for an occasional missed dose [1.4.5, 1.6.3].

No, you should never take two doses at once to make up for a missed one. This can increase the likelihood of experiencing side effects [1.2.2, 1.7.3].

No. You should never stop taking Biktarvy without consulting your doctor. Stopping for a week can lead to a significant viral rebound and a high risk of developing drug resistance [1.2.1, 1.2.8]. Always plan to have enough medication for any trips.