Q and A


Is it ok if I take my meds 15 or 30 mins late?

Do you have to take your arvs at exactly the same time each day? Will for example 30 mins (or even an hour) each way have any impact whatsoever on the suppression of the virus or cause resistance? I am worried as even though I take them every day some days it is 15 or 30 mins later or earlier than the previous day.


Thank you for your question.

It is sometimes difficult to take your meds at the exact same time everyday.

Even when starting, there is a window of about an hour either side of your target time when it is still fine to take them.

For example, if you want to take your meds every night at 10 pm, then any time between 9pm and 11pm will be fine.

Everyone has a few times when we forget our meds though.

The less this happens the better. But if it does happen once in a while then there is nothing to worry about. If you forget in the future, take them as soon as you remember. However, if this is already close to the next dose DO NOT take a double dose.

Once you get an undetectable viral load, especially if it has been undetectable for several years, you have more flexibility. This partly depends on which drugs you are using.

Some once daily drugs (including tenofovir DF, emtricitabine and efavirinz) have long half-lives. This means drug levels stay in your body for long enough to cover being several hours late or even missing a dose completely.

Several studies are looking at whether reduced dosing might be safe – for example by only taking ART for four days a week. We need bigger studies before we know if this is safe though.

Note: this question was updated in October 2016 from and original answer in April 2011.


  1. Simon Collins

    Hi Preety, please don’t worry about this. It is okay to be an hour or two early (or late) without it affecting the chance PEP will work.

  2. Preety

    Hi I took my pep 24 min late than usually time can it reduce the efficiency of pep plz help me..

  3. Lisa Thorley

    Hi Innocentia,

    What’s the name of the ARVs that you’re taking? How long have you been taking them for?

  4. Innocentia

    Im experiencing alot of fever after taking the medication and i take it during the day im weak and dont have appetite. How long until this sickness fades away. And i have to go to work how do i avoid feeling dizzy and weak.

  5. Lisa Thorley

    Hi Pruddy,

    Yes you can take your pills a bit later, this won’t be a problem.

  6. Pruddy

    Im taking my pills at 9pm everyday,what will happen if I forgot and remember around 1am can I take a dose.

  7. Lisa Thorley

    Hi Nsubuga,

    No this doesn’t have any effect. As long as your viral load is undetectable it’s Ok to take your meds a few hours either side of your normal time.

  8. Nsubuga

    Am supposed to take my Arvs at 11:05pm but some times i take it late at 11:12pm, does it have any effect.

  9. Lisa Thorley

    Hi Cynthia,

    Missing a dose won’t make any difference, you’ll be fine.

  10. Cynthia

    Hi .I’m worried I’m on 1 morning tablet I took it 14 hrs and 15 minutes late I’m feeling very nausea please help I am undetected Im living with Hiv since 2008. Thank you


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