Dr Beth McElroy is race doctor for the Manaslu Trail Race, a staged trail race in Nepal, in November. She’s written the following advice for participants ofd the Manaslu Trail Race.
1) Why is Diamox used?
Diamox (Acetazolmide) is a medication used to help prevent Acute Mountain Sickness (AMS) which can occur in visits to above 2,500 metres. The symptoms of Acute Mountain Sickness can cause headache, fatigue, nausea and vomiting and difficulty sleeping. If ignored or untreated it can progress to oedema (fluid) of the lungs or brain. These are known as HAPE or HACE and must be treated by a doctor.
2) How does Diamox work?
Diamox works to reduce the headache associated with AMS by increasing the rate at which we breathe and the speed at which our kidneys get rid of waste. It acts similarly to how the body would work to acclimatise but is able to help the body make these adaptations more quickly. As a result Diamox does NOT mask the symptoms of altitude symptoms as is sometimes thought!
3) When is taking Diamox a good idea?
Taking Diamox is a good idea when there is a rapid ascent to altitude. This is the case with unacclimatised individuals who ascend terrain in a short time frame, where there is intense exertion at altitude and where the altitude gain is above 300-500 metres per day.
4) Who should not take Diamox?
People with Sulphur allergies should not take Diamox. Sulphur can be found in some antibiotics, certain diabetic medication and certain diuretic medications, often known to patients as ‘water tablets’. Please consult your GP if you are concerned you may have an allergy to one of these medications.
5) How should I take Diamox?
The dose of Diamox to prevent altitude sickness is 125mg twice a day. This usually equates to half a (250mg) tablet, taken in the morning and again in the evening before sleep. In people who haven’t taken Diamox before, there must be a home trial, of ideally two days, before travel to the area of altitude. If there are no unpleasant side effects, the tablet must be commenced three days before staying at 3,500m and continued thereafter until reaching the maximum altitude.
6) What are the side effects of Diamox?
Diamox can cause tingling of the fingers, face or feet. This is normal but can be occasionally unpleasant. Dizziness, vomiting, rashes, drowsiness, confusion and allergic reactions can be associated with this medication but are rare. Carbonated drinks and can taste funny as a result of taking this medication. Please note: Alcohol is not allowed at altitude but by the time you are back at the hotel after the race/expedition, the effects of the Acetazolamide on your taste buds will have worn off if you want to have a celebratory drink!
7) Where can I get Diamox from?
Diamox (Acetazolamide) should be prescribed by your GP or in countries like Nepal can be bought over the counter but beware of counterfeit medications. GP’s in the UK/Europe may charge you a small amount for this prescription. Occasionally online pharmacies can provide this medication after a brief phone consultation. In the UK a reputable service with patient recommendation is: http://www.doctorfox.co.uk/altitude-sickness/. You should obtain a big enough supply to last you for a 2 day trial in your home country and then enough for prophylaxis for the duration of the expedition. The prescription should read thus:
‘Acetazolamide 250mg tablets. Half a tablet twice a day for 14 days’.