Q and A


How do I time my meds when travelling?

I am currently on Atripla (since Feb 08) and remain undectable.

Next week I am taking a vacation and we are going from the UK to the US. There is a 6hr time difference with the US being behind 6hrs. I usually take my Atripla around 11pm at night. I am really frightened and concerned and dont know what to do?

If I don’t adjust the times then i will be taking my meds at 5pm US time which will mean I could be wiped out from the side effects for the rest of the evening? However, I dont want to risk taking them at 11pm US time, as it will mean that I am 6hrs late taking my Atripla, which could lead to resistance. What should i do?

Thanking you in advance and i would really appreciate if someone was able to give me advice as we travel in a few days.


Thanks for your question.

For someone who is using Atripla (efavirenz+tenofovir+FTC) and has had an undetectable viral load for many months (or years) it is probably easiest to just switch to US time on your first night.

Although this risks low drug levels for up to 6 hours, this is just like forgetting one days meds, which even someone with the best adherence is likely to do at least once or twice. Although this isn’t the best scientific answer, in practice, missing one dose for a few hours is unlikely to do any harm – see this previous question on this.

This approach is also supported by a study called FOTO (Five On Two Off) where people with undetectable viral load on Atripla, were randomised to either continue on 7-day dosing or change to taking meds for 5 days a week and not for 2 days at weekends. After one year, the people on the 5-day strategy all still had undetectable viral load.

While I think that the FOTO study is too small a study to support people switching routinely to the 5 days on/2 days off strategy, I think it provides interesting evidence to support the general safety from extending, or missing, one dose of Atripla.

Scientifically, and for people using other combinations, the main options when travelling to different time zones is either to stay on UK times (ie taking them at different local times – 5pm rather than 11pm UK time n your example) or to switch to the same time of day in the new time zone. For anything other than a very short trip, it is usually easier to change to the new time zone – ie so if you take meds at 11pm in the UK to take them at 11pm on your holiday time zone.

When changing the schedule the main principal is that it is easier and safer to bring forward your dose time then is is to extend it. For a twice-daily drug you don’t want to leave it longer than 12 hours, but it is fine to bring one dose forward, even by 6 hours, if that gets you on the same local time at your destination. With a once-daily drug, you don’t want to go past 24 hours, but could bring it forward by 6, 8 or even 12 hours.

Although bringing froward a dose will give you slightly higher levels of each drug, this is very safe for such a short period.

When returning to the UK, bringing the dose forward to get you on UK time with your first dose is fine for the same reasons.

Reference: 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. 5th IAS Conference, 2009. Abstract MOPEB063.


  1. Roy Trevelion

    Hi Pat,

    Please talk to your grandson’s doctors about his epilepsy meds. This website resource is for people who are HIV positive and taking HIV medication.

  2. Pat

    My 15 year old grandson takes meds for epilepsy at 7pm and 7 am daily. He will be traveling to Ireland in November for 5 days. There will be a 5 hour time difference. How should he adjust his time to take his meds so they are still 12 hours apart but not once in the middle of the night?

  3. Lisa Thorley

    Hi Nick,

    Its fine to take your meds at the local time of 11pm, that is if you want too. And yes you can take it at 5pm when you arrive, or you could even wait until 11pm, this wouldn’t be an issue.

  4. Nick

    Hi,I’m taking Lami+Efav+Teno once a day in China,I always take it at 11:00 p.m.I’m gonna travel to Europe for 2 months and considering it will be a long journey,I wanna follow the local time,China is 6 hours faster than in Europe in summer,can I do it like this?:On the arrival day,I take them at 5 p.m in Europe and then I take it again at 11 p.m,from the next day for this two months I’ll always take it at 11 p.m

  5. Roy Trevelion

    Hi Rue,

    It’s probably best just to stick to the local time and take them at 9pm when you’re in Dublin. It depends on how long it takes you to travel from the Philippines to Dublin too. If necessary you can skip just one dose rather than take two doses in a 24 hour period.

  6. Rue

    Hi, Good Day. I’m taking Lami+Efav+Teno. I’m taking the meds during 9pm in the Philippines. My concern is I’ll be migrating to Dublin and the Dublin is 8 hrs late from the Philippines. How can I adjust the time of my medication. Thanks

  7. Roy Trevelion

    Hi Lizza,
    There’s quite a lot of info below. London is 8 hours ahead of California, so you can work out what’s best from the information given here. You can talk to your doctor about whether travelling this distance can affect your mood and abililty to take your meds.

  8. Lizza

    I will be travelling across a 9-hour time zone (London to California) and I have bipolar disorder. Any advice?

  9. Lisa Thorley

    Hi Neil,

    Its fine to take it at 9.30pm US time, it won’t cause you any problems. Once you’re home, just take it as normal.

  10. Neil

    I normally take my single combination tablet at 9:30 p.m. each night. So when I travel to the United States -6 hours what I do is:
    three days before I travel I take my medication one and a half hours later than normal i.e 11 PM.
    The next night I take my medication two hours later at 1 AM.
    The day I’m due to travel I take my medication at 3 AM and then I take my medication at 9:30 p.m. United States time.


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