• Review by a qualified doctor
  • Including prescription
  • Next-day delivery included

How does Diamox work?

Acetazolamide, the active ingredient in Diamox is a carbonic anhydrase inhibitor as well as a diuretic. This treatment aims to influence blood acidity levels. By doing this it can reduce the risk of symptoms such as headaches.

In addition to influencing blood-acidity levels, it also produces bicarbonate, which gives it its diuretic effect, thereby ensuring that the water levels in blood remain at a healthy level. Both these actions don't just help to reduce the mild discomforts associated with this condition but can also reduce the risk of a patient developing more serious complications.

Who should use Diamox?

Although generally safe to use, this can't be taken safely by everybody. People who should not use Diamox are those who are allergic or sensitive to the ingredient acetazolamide or any of the other ingredients contained in this medication. It's also unsuitable for pregnant or breastfeeding women to use, those with low blood potassium or sodium levels, patients with liver or kidney conditions or who have been diagnosed with Addison's disease, suffer from gout or have lung problems.

When completing your online consultation with 121doc, you should make sure that you provide us all the health information that is asked, as this will provide our doctor with the suitable data to make the best recommendation for you. our doctor will also want to be sure that you'll be using this treatment safely and not as an alternative to traditional acclimatisation measures.

How do you take this medication?

This medicine is available in a 125mg or a 250mg dose. The tablets should be swallowed whole, with a glass of water alongside a meal. The dosage that will be prescribed to you will depend on your individual needs and current health, although the traditional recommendation will be up to a maximum of four tablets a day. As it is a preventative treatment, you'll likely have to start taking your acetazolamide tablets a couple of days before you start ascending.

It is essential that you follow traditional methods for avoiding altitude sickness and that you don't change your dose without speaking to your doctor first.

What are the side effects of Diamox?

All prescription medications have a minor risk of side effects, but it doesn't mean that they will appear in everyone who uses this treatment. Side effects that have been reported are nausea, vomiting, dizziness or rash, but luckily these are mild and shouldn't be lasting. You should, however, be aware that one of the rare side effects of this treatment is an allergic reaction, for which you will need to seek immediate medical help.

How to order online

You can prepare for your climb by ordering Diamox safely from 121doc. Here we ask all our patients to complete a completely free and confidential consultation form, as this will allow our licensed doctor to provide a prescription based on your individual needs. This means that our doctor may choose not to provide you with a prescription if this is a safer option. If a prescription is issued, it will be sent straight to our pharmacy, where a registered pharmacist will dispense it. It will then be packaged and dispatched via secure courier service for next day delivery. All orders include a free consultation and there is no additional charge for delivery.

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How does it work?

Select Select your treatment


Select a condition here or use the top menu. For every condition, we provide you with information as well as the treatments we currently offer. If you don’t know which is best for you, just click the 'Advise-me' button.


If you know what you want, the quickest way to find a specific medication is to use the search bar here.


Every order starts with an online consultation. We will ask you medical questions to make sure only treatment that is safe and effective is prescribed. We take into account your lifestyle, health and any other medications you’re currently using.

The consultation is completely free, and takes between 5 and 10 minutes of your time.

All your information is safe with us. We don’t share it with anyone unless you want us to.


If you need any guidance, you can call, message or email our customer service team via the ‘How can we help you?' section here.

Prescribe Redeem your prescription


As soon as you place the order, one of our doctors will review your consultation. On working days, this usually takes around one hour.


If the doctor has any additional questions, you will receive a phone call and an email. We understand you might be at work or busy. Our customer service representatives are always discreet and can call back at a more convenient time if necessary.

Our emails never contain any personal or medical information, only a link to your private account on our website (where you will find your messages).


Once our pharmacy receives your prescription, you will get a second email with your package tracking code.

Deliver Expect your delivery the next working day.
Always free. Discreet packaging.
Free next-day delivery


All orders include next-day delivery. Alternatively, you can select a delivery date that suits you better.


We also provide a free UPS Access Point service. Pick up your package from one of many collection points across the UK.

With your tracking code, you will know the estimated delivery time. All we need is your signature (or a friend‘s or relative’s).


All parcels are plainly labelled; there is no logo or any indication of its contents. Inside, you will find your treatment as well as a patient leaflet in your chosen language.

Repeat Subscribe and save with our repeat service. Never miss a dose again.
10 to 15% off


With 121doc’s Subscribe & Save service, you can automatically receive your treatment every few weeks or months.

The order will be generated by us, using the information you provided (including delivery frequency). You don’t have to do anything. Payment is taken two days before shipping.


There are two ways to subscribe. The first is during the order process. The second is via your profile here.

You can cancel or amend your repeat prescriptions at any time.


There are no sign-up fees with this service. Plus, you get a 10% discount off all future prescriptions, increasing to 15% after six orders!