Q and A


Should I worry about an Atripla dose that is 4 hours late?

I was diagnosed with HIV just barely over a year ago. Because my CD4 count was low my doctor prescribed Atripla.

Within 3-4 months of being on the drug my CD4 count had jumped up to over 800 (from 370) and my viral load dropped to undetectable. I’ve been taking it really carefully and on-time or within an hour and my last labs showed that my CD4 count was reconstituted and my VL was still undetectable.

Last night I had my first blunder. I went out to a birthday party with at a friends house and I forgot my pill at home. It was about 4 hours late. Could this mishap unravel all work I had done to keep my CD4 up?



From the circumstances you describe there is no need to worry. Being late with one dose will not have affect your health in any way.

It is only if you regularly miss doses or are late with Atripla that the chance of developing resistance becomes a real concern.

The three drugs in Atripla (efavirenz, FTC and tenofovir) all have good concentrations at the end of each 24-hour dose to cover you for a few hours either way.

One study included this combination in an unusual combination. The study was called FOTO for Five days On Two days Off, and it followed people taking Atripla on weekdays and missing the two days at the weekends. After one year everyone still had a viral load that was undetectable (less than 50 copies/mL).

No treatment guidelines recommend following the FOTO strategy, but it is a good example of how an occasional missed dose of Atripla is unlikely to do any harm.

FOTO STUDY: Cohen C et al. The FOTO study: The 48 week extension to assess durability of the strategy of taking efavirenz, tenofovir and emtricitabine Five days On, Two days Off (FOTO) each week in virologically suppressed patients. IAS 2009, Cape Town. Abstract MOPEB063.


  1. Joseph

    I missed my arv meds twice. 1st time 3 hours late and last night 5 hours late. Can I change the times taking my medication or is it unsafe

  2. Lisa Thorley

    Hi Jack,

    You’ll be fine. This won’t have caused your viral load to rebound.

  3. Jack

    Hi i missed taking my ARV for 5hrs (efavirenz,Lamivudine,tenofovir) is it bad?

  4. Thorsten

    Hi same happen to me , got 90Min late of taking Atripla but after reading this. I’m not anymore stressed .thank you

  5. Simon Collins

    First you need to take an HIV test to find out whether you have HIV or not.

    If you have already tested positive, you need to see a doctor who will text your CD4 count (and other tests). The information from these tests will determine whether you need treatment yet.

  6. ddssfff

    hiv positive what i do?

  7. Charlotte Walker

    Hi James,

    Please try not to worry. A VL increase of 10 is so small that it is insignificant and does not mean your meds are not working. VLs do fluctuate slightly even when they are below 50cells/mL3 so this is perfectly normal. Your CD4 count is increasing which is good and your viral load is coming down nicely. You have nothing to worry about.


  8. james

    I have been on Atripla for 8months. B4 starting cd4 7 vl 74000. First 3 month lab cd4 28 vl 120. 2nd lab cd4 86 vl 130!!! I go back in 3 days for next labs. That means I would have been on Atripla 8 months 9 days..I have been about 7 hrs late once since my last lab, and 5 hrs late once b4 last labs. My question is since my vl went up from120 to 130 does that mean the Atriplas not working?? Also if my doctor said noting about vl going up.,should I be worried? I’m so stressed out…

  9. Charlotte Walker

    FOTO only looked at specific drugs – Truvada and efarvirenz. These drugs stay in the body longer than many other drugs which is perhaps an important aspect for why the results were promising. Most people miss or are later with their meds occasionally without this causing any harm.

    If your viral load is undetectable, one missed dose will be fine. Take your meds when you remember the missed dose, unless you are close to you next dose. You should not double the dose when you next take your meds.

  10. Jeremy

    Does the FOTO work for any other combination of meds? I am on truvada, atazanavir & ritonavir. How crucial is a late or missed dose with that combination?


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