“Drugs dose BID vs q 12 hours – taken twice a day vs. every 12 hours – have more flexibility in adjusting the time that they are taken,” Professor Goad noted. “For example, a traveler to India for a 2-day business meeting will spend up to 24 hours in transit each way. Thus, for long-haul flights, patients should consider not disrupting their regimen and to take their medications in-flight. For a short-duration trip, it will also be less confusing for patients on fixed regimens (that is, taking their medication every eight or every 12 hours) to not account for time zones and continue to take their medications with the appropriate intervals.”

“Remember, drugs don’t feel time zones,” Dr. Goad said. 

When dosing is less stringent—for example, “at bedtime”—patients can take medications at their bedtime in a new time zone because they will tend to sleep for roughly the same amount of time, Dr. Goad explained.

Antiretroviral regimen dosing is just one important consideration for HIV+ travellers, alongside pre-travel vaccines and cART interactions with antimalarial prophylactic medications, the authors noted; patients should discuss travel plans with their physicians.1 Discussions should include contingencies, such as what to do if a dose is missed during a flight.

“Under guidance by a physician or pharmacist that is monitoring drug levels and viral loads, they may recommend extra doses to optimize therapy,” said Dr. Goad. “However, patients should not choose to do that on their own.”

It is a general rule of travel medicine that “if a dose was missed and it is now almost time for the next dose, the patient should skip the missed dose and just take the next one,” Dr. Goad advised. “This is a general recommendation for all medications. Extra doses are generally never recommended.  Missed doses should be taken as soon as they are remembered, but skipped if it is time for the next dose.”

Although other patient populations face similar issues during international travel, the guidelines set out in the AIDS paper cannot necessarily be safely extrapolated to other conditions and medications, Dr. Khoo was quick to point out. Delayed or supplemented medication dosing is “very much drug- and disease-specific,” he warned. 


1. Lewis JM, Volny-Anne A, Waitt C, Boffito M, Khoo S. Dosing antiretroviral medication when crossing time zones: a review. AIDS. 2016;30:267-271. DOI: 10.1097/QAD.0000000000000920. http://journals.lww.com/aidsonline/Fulltext/2016/01140/Dosing_antiretroviral_medication_when_crossing.13.aspx