Altitude Sickness Tablets
Do I need altitude sickness tablets?
Altitude sickness is about how high you go and how fast you get there — fitness is no protection at all. Here is the honest picture.
| Traveller | Who should consider it | Doses & schedule |
|---|---|---|
| Advised Treks & climbs above 2,500m | Kilimanjaro, Everest Base Camp, the Inca Trail and the High Atlas all push well past 2,500m — the height where altitude sickness starts, with risk rising sharply on fast ascent profiles. | 1 tablet twice a day, starting 1–2 days before ascent. |
| Advised Flying straight into high cities | Landing directly in Cusco (3,400m), La Paz (3,600m) or Lhasa skips acclimatisation entirely — the classic way to get caught out. | Same course, started before you fly. |
| Consider Anyone it has hit before | If altitude sickness struck you at a given height once, it is likelier to strike again at similar heights. | Course plus a slower ascent plan. |
| Not usually needed Trips staying below 2,500m | Most city breaks, safaris and beach holidays never approach risk altitude — plainly said. | No tablets needed. |
The price is per tablet on the travel clinic price list — your total depends on your ascent profile, confirmed at the free consultation.
What is altitude sickness?
Altitude sickness — acute mountain sickness, or AMS — happens when you climb faster than your body can adapt to thinner air. Above about 2,500m, less oxygen reaches your blood with every breath; the result, typically 6–12 hours after arriving at altitude, is headache, nausea, dizziness, fatigue and broken sleep.
Most cases are miserable rather than dangerous, and settle with a rest day at the same height. But pushed higher, AMS can progress to swelling of the brain or fluid on the lungs — genuine emergencies where immediate descent is the treatment. The golden rules: never ascend with symptoms, and never ignore someone who is getting worse.
Prevention is a partnership: a sensible ascent profile with rest days does most of the work, and a prescription tablet that speeds your body’s acclimatisation covers the rest — particularly valuable for fixed itineraries and flights straight into high cities, where slow ascent isn’t an option.
How altitude sickness tablets work
The tablets gently deepen your breathing, helping your body take on more oxygen and adjust to altitude faster — they accelerate acclimatisation rather than masking symptoms.
| Situation | Who should consider it | Doses & schedule |
|---|---|---|
| Standard course | One tablet twice a day, starting 1–2 days before reaching altitude. | Continue for 2–3 days at your highest sleeping altitude, or as advised. |
| Trek itineraries | The course is planned against your actual ascent profile — rest days matter as much as tablets. | Bring your day-by-day itinerary to the consultation. |
| Not suitable for everyone | A sulfonamide allergy and certain conditions rule the tablets out. | Checked at the consultation — supply is not guaranteed. |
These are prescription-only tablets, supplied after your pharmacist consultation — and they never replace a sensible ascent plan. Severe or worsening symptoms at altitude mean one thing: descend.
How our travel clinic works
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Choose a time that suits you — same-week appointments are usually available, and families can be seen together in one visit.
Personalised risk assessment
Your pharmacist reviews your itinerary, health history and previous vaccinations against current UK travel health guidance, and agrees a plan with you.
Planned around your ascent
Your course is written against your actual itinerary — when to start, what to take at your highest camps, and what symptoms mean it’s time to stop climbing.
Where does altitude matter?
The classic high-altitude trips all have full travel-health guides here — altitude advice sits alongside the vaccinations for each:
Frequently asked questions
At what height does altitude sickness start?
From about 2,500m — roughly the height of Cusco’s valley floor — with risk climbing steeply above 3,500m. It’s about the altitude you SLEEP at and how fast you got there; fitness offers no protection.
How do the tablets work?
They gently change your blood chemistry so that your breathing deepens, letting your body take on more oxygen and acclimatise faster. They speed adaptation rather than hiding warning symptoms.
Do the tablets mask the danger signs?
No — that’s their key advantage. You still notice genuine deterioration, which is what keeps trekkers safe. Any severe or worsening symptoms at altitude mean descend, tablets or not.
I’m climbing Kilimanjaro — do I need them?
Most Kilimanjaro itineraries ascend faster than textbook acclimatisation allows, which is why so many climbers take the tablets. Bring your route and number of days — the 7–8 day routes are dramatically kinder than the 5-day ones.
Are there side effects?
Tingling fingers and toes and a strange taste to fizzy drinks are the classic, harmless ones; the tablets are also a mild diuretic, so drink well. The consultation checks the rest, including the sulfonamide-allergy rule-out.
What should I do if symptoms start anyway?
Stop ascending and rest at the same altitude — most mild cases settle in a day or two. If symptoms are severe, worsening, or include confusion, breathlessness at rest or a wet cough: descend immediately and seek help.
Rated by 1,200+ patients of our Camberley pharmacy and clinics.
GPhC registered pharmacy 1105418 · Superintendent pharmacist Jirina Thielens (GPhC 2069634).
This guide follows UK national travel health guidance (TravelHealthPro / NHS) and was last reviewed in August 2026. Recommendations can change — your consultation always reflects the latest advice.
Going high? Acclimatise on purpose.
Altitude sickness prevention planned against your exact itinerary — consultation, prescription and supply in one visit in Camberley.
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