Acetazolamide helps to reduce increased eye pressure (glaucoma).
If you feel sleepy after taking the tablets/capsules, do not drive and do not use tools or machines until you feel better.
There are a number of common side-effects, but they are not usually serious.
|Type of medicine
|A carbonic anhydrase inhibitor
|Diamox®; Diamox® SR
|Tablets and modified-release capsules
An increase in pressure within your eye can lead to damage to the optic nerve at the back of your eye. When this occurs it is called glaucoma. Glaucoma can lead to a loss of vision if it is not treated. Treatment with acetazolamide helps to reduce eye pressure, and this helps to prevent further eye damage. You will also be given other medicines to help reduce the pressure in your eyes, commonly as eye drops.
Acetazolamide works by blocking the action of an enzyme called carbonic anhydrase. Blocking this enzyme reduces the amount of fluid (called aqueous humour) that you make in the front part of your eye, and this helps to lower the pressure within your eye.
Acetazolamide is sometimes prescribed for other conditions which are not covered by this leaflet. If you have been prescribed it to remove excess water from your body, to prevent altitude sickness or to help treat epilepsy, speak with your doctor if you need further advice.
Before taking acetazolamide
Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking acetazolamide it is important that your doctor knows:
- If you are pregnant or breastfeeding.
- If you have liver or kidney problems, or difficulty passing urine.
- If you have diabetes mellitus, a condition which causes raised blood sugar levels.
- If you have breathing problems.
- If you have problems with your adrenal glands, such as Addison's disease.
- If you have been told you have low amounts of potassium or sodium, or high levels of chloride in your blood.
- If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
- If you have ever had an allergic reaction to a medicine. It is particularly important that you tell your doctor if you are allergic to sulfonamide antibiotics.
How to take acetazolamide
- Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The manufacturer's leaflet will give you more information about acetazolamide and a full list of the side-effects which you may experience from taking it.
- Your doctor will prescribe you a dose that is suited to your condition, so take acetazolamide exactly as your doctor tells you to. If you are taking tablets, it will be between 1-4 tablets daily, taken in divided doses over the day. If you are taking capsules, it will be 1 or 2 capsules daily. Your dose will be printed on the label of your pack to remind you what your doctor said.
- If you are taking capsules (brand Diamox® SR), they are specially formulated to release the medicine they contain slowly during the day to give a more even effect. Do not chew or open the capsules as this will stop them from working as intended.
- Try to take your doses at the same times of day each day, as this will help you to remember to take acetazolamide regularly. You can take your doses either just before or just after meals.
- If you forget to take a dose, take it as soon as you remember unless your next dose is due. If your next dose is due, then take the dose which is due but leave out the forgotten one. Do not take two doses together to make up for a missed dose.
Getting the most from your treatment
- Keep your regular appointments with your doctor so that your progress can be monitored.
- Your doctor will tell you how long you will need to take acetazolamide for. It is not generally recommended for long-term use, so if you need to take it over an extended period of time, your doctor will want you to have some blood tests.
- You should also let your doctor know if you develop an unusual skin rash while you are on acetazolamide.
- If you buy any medicines, check with a pharmacist that they are safe to take alongside acetazolamide.
- If you are having an operation or any medical treatment, remember to tell the person carrying out the treatment which medicines you are taking or using.
Can acetazolamide cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with acetazolamide. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.
|Common acetazolamide side-effects
|What can I do if I experience this?
|Feeling sleepy, tired or dizzy
|Do not drive and do not use tools or machines until you feel better
|Upset stomach, feeling sick (nausea), diarrhoea
|Stick to simple meals. Try taking the tablets after meals if you are not already doing so
|Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headaches continue, let your doctor know
|A metallic taste, lack of appetite, looking flushed, feeling irritable, feeling thirsty, tingling feelings, passing urine more often
|If any of these become troublesome, speak with your doctor
If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist for further advice.
How to store acetazolamide
- Keep all medicines out of the reach and sight of children.
- Store in a cool, dry place, away from direct heat and light.
Important information about all medicines
Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.
This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
If you have any questions about this medicine ask your pharmacist.
Further reading and references
Manufacturer's PIL, Acetazolamide Tablets 250 mg; ADVANZ Pharma (formerly Concordia International), The electronic Medicines Compendium. Dated December 2019.
Manufacturer's PIL, Diamox® SR 250 mg Capsules; ADVANZ Pharma (formerly Concordia International), The electronic Medicines Compendium. Dated June 2019.
Medicines Complete BNF 86th Edition; British Medical Association and Royal Pharmaceutical Society of Great Britain, London.