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. Roy Trevelion

    Hi Success,

    Forgetting take take our meds very occasionally is fine. But if it happens regularly it can mean that the ARVs will stop working as well as they should.

    It’s a good idea to talk to your doctor about this. And if it’s difficult to take your meds on time you and your doctor can discuss this.

    Here’s the i-Base guide to how to remember to take ARVs.

  2. Success

    What happens when I forget taking ARVs 2 times a month

  3. Roy Trevelion

    Hi Zaza,

    Here in the UK, women are recommended to use formula rather than breastfeed. This is even when the mother is on treatment and viral load is undetectable.

    But in some countries, breastfeeding is recommended if viral load is undetectable. This is related to other risks to the baby.

    Please talk to your doctor and nurse about the recommendations in your country.

    I hope you are getting support and information about HIV, and that everything goes well with you and your new baby.

  4. Zaza

    Good day My name is Zaza

    I tested positive during my pregnancy I am formula feeding its been 1 month now can I switch to exclusively breastfeeding? Can this risk my baby’s health?

  5. Lisa Thorley

    Hi Thandeka,

    Yes you should continue taking your meds at the normal time. You may have felt dizzy as you took them during the day.

  6. Thandeka

    Hi I yesterday I forgot to drink my tribuss so I remember today around about 13hours so I decided to take them BT now I feel dizzy must I take another1 coz my normal time is 20h00

  7. Lisa Thorley

    Hi Priscilla,

    When you say on time, what do you mean? If you’re just talking about a few hours either side of your normal time, this is OK. As you’re pregnant, you may find the following helpful. http://i-base.info/guides/pregnancy

  8. Priscilla

    Hi I started my treatment 2019 n now I’m pregnant but I don’t normally take my pills on time is it save for my unborn baby

  9. Lisa Thorley

    Hi Sarah,

    When someone first starts medication it’s important that they try and take it on time. Once you’re viral load is undetectable, there’s then some flexibility with regards to time. By this I mean you’ll be able to take your meds a few hours either side of your normal time.

    If you’re having issues with remembering to take your meds, the easiest thing to do is to set an alarm on your phone.

    Meds need to be taken at a time that works for you and your life style. However, if the ARVs you’re taking contain efavirenz it’s advised to take these in the evening. This is due to the possible side effects as the following explains: http://i-base.info/guides/1561

  10. Sarah

    I tested positive on march 2020 and I am pregnant,at times I forget to take my art at night that is at ten.is it okay to take the pill in the morning?I have forgotten twice so far..what percentage is there that my baby could turn positive.
    What is the risk of taking arv that is supposed to be taken at night to take in the morning


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