Travel can seriously mess with key mechanisms of oral contraceptives such as The Pill, rendering travellers susceptible to unplanned pregnancy.
The most direct way they fail is through malabsorption due to travel maladies that induce diarrhoea or vomiting. Antimalarial doxycycline and high doses of vitamin C found in some jet lag pills can also inhibit the pill’s efficacy. Less directly, the time zone changes in long-haul travel can throw the cycle out of whack. Missing a dose by just 12 hours can throw the system off.
Advice for overseas travel
The going advice is to continue taking the Pill at ‘home time’ (not local time at your new destination) and gradually adjust to your new time zone. If you do miss a dose, The Travel Doctor TMVC, a specialist travel clinic network, advises applying the seven hormone days rule.
In plain speak, take active pills for the next seven days, during which time you’ll use condoms as backup.
NOTE: Women taking the Pill are more susceptible to blood clot formation, largely due to the oestrogen, and need to be especially aware of the risk ahead of long flights.
Women aged over 35 and smokers are especially susceptible. If you’re staying above 3,700 metres for more than four weeks, ask your GP about alternative contraceptives as the longer you spend in conditions that maximise clot risk, the greater the odds of it materialising.