Over-the-counter motion sickness medicine: what you can actually buy

In the US, two ingredients cover almost every box on the shelf: dimenhydrinate (Dramamine Original Formula) and meclizine (Bonine, Dramamine Less Drowsy). The federal over-the-counter rules also allow cyclizine and diphenhydramine for motion sickness, but cyclizine is not generally sold in the US and the common diphenhydramine box is labeled for allergy. In the UK the pharmacy options are different: hyoscine hydrobromide tablets, cinnarizine, cyclizine and promethazine. Canada's shelf staple is Gravol (dimenhydrinate), and Australia's is Travacalm (dimenhydrinate with hyoscine, or hyoscine alone), sold from the pharmacy counter.

For a passenger who can plan ahead, the same two US ingredients: dimenhydrinate or meclizine, taken before the drive as the label directs. The CDC Yellow Book says motion sickness medicine is most effective before exposure, not after symptoms start, so a tablet swallowed once the nausea has arrived does less. Both can make you sleepy, so they suit the passenger, not the driver. For the moment it hits anyway, a drug-free option built for use after symptoms start is the other half of the plan.

Dimenhydrinate and meclizine are the over-the-counter choices in the US. The CDC Yellow Book pairs them with milder motion, and reserves the scopolamine patch, which is prescription-only in the US, for longer trips with moderate to intense motion. Meclizine's label is built around a long duration, so one dose covers a day, which is why it keeps coming up for cruises. Take it before you board as directed, and ask the ship's medical centre or a pharmacist if you are unsure.

There is no single best one. Airsickness is uncommon on smooth commercial flights, so many people need nothing. If you are prone to it, the usual over-the-counter choice is an antihistamine tablet, dimenhydrinate or meclizine in the US, taken before boarding as the label directs. Both list drowsiness, which some travelers welcome on a long flight and others cannot afford on arrival. A pharmacist can help you choose between them.

No. Every ingredient the US rules permit carries a drowsiness warning: marked drowsiness for dimenhydrinate and diphenhydramine, and may cause drowsiness for meclizine and cyclizine. Meclizine is marketed as less drowsy, which is a comparison with dimenhydrinate, not a promise of none. The newer non-sedating allergy antihistamines are not used for motion sickness because they do not work for it. If you need a clear head, the drug-free routes are seat choice, a view of the horizon, no screen, and sound therapy through headphones from the passenger seat.

Not in the US. The scopolamine patch is prescription-only there, and the over-the-counter rules for motion sickness list four oral ingredients and no patch. In the UK the NHS says pharmacies sell patches for adults and children over 10. Patches sold without a prescription in the US are herbal or device products, not approved motion sickness medicines. Our patch guide covers the difference.

Read the age line on the box, because it differs by ingredient. The US rules say dimenhydrinate is not for children under 2 unless a doctor directs, cyclizine and diphenhydramine not under 6, and meclizine not under 12. The CDC Yellow Book adds that children under 2 do not usually get motion sickness at all, that medicine for children should be used with caution, and that over-sedating a young child with an antihistamine can be life-threatening. A pediatrician or pharmacist should make this call.

Before. The CDC Yellow Book is direct about it: medication is most effective when taken before exposure rather than after symptoms begin, and tablets need time to be absorbed. Each label states its own lead time, from about half an hour for some hyoscine tablets to an hour or two for others. Once nausea has started, the practical steps are the horizon, fresh air, no screen and a still head, plus a drug-free option designed for that moment.

Not according to the CDC Yellow Book, which says ondansetron and granisetron are not effective against motion sickness. They are prescription medicines for other kinds of nausea. The medicines that do work for motion are the antihistamines and scopolamine, so a leftover anti-nausea prescription is not a substitute for an over-the-counter motion sickness tablet.

They are different drugs rather than different strengths of one: Dramamine Original is dimenhydrinate and Bonine is meclizine. Dimenhydrinate's label warns of marked drowsiness and it acts for a shorter time; meclizine's label says it may cause drowsiness and it lasts longer. The CDC Yellow Book puts the two in the same tier of option for mild to moderate motion. Which fits you depends on the trip length and how much sleepiness you can accept, which is a pharmacist question.