Pharmacy Guide
Patient leaflets and SmPCs, drug interaction checker, official dosages and NHS pharmacy opening hours — all in one place.
Pharmacy Guide
Patient leaflets and SmPCs, drug interaction checker, official dosages and NHS pharmacy opening hours — all in one place.
Diamox 250mg Tablets
⚠ This medicine appears to have been discontinued
The electronic medicines compendium (emc) no longer publishes a Summary of Product Characteristics for this product, which usually means it is no longer marketed in the UK. The patient leaflet below is kept for reference, but the product may not be available.
If you were prescribed this medicine, other products containing Acetazolamide may still be available. Do not stop your treatment — ask your pharmacist or GP what to use instead.
What it is and what it is used for
for Diamox® 250mg Tablets (referred to as Diamox 250mg Tablets throughout this leaflet) contain the active substance Acetazolamide. This belongs to a group of medicines known as carbonic anhydrase inhibitors. Diamox 250mg Tablets are used to treat:
- glaucoma (a condition of the eye), by reducing the pressure within the eye
- abnormal retention of fluids (Diamox 250mg Tablets acts as a diuretic)
- epilepsy (fits or convulsions).
What you need to know before you take it
e Diamox 250mg Tablets Do not take Diamox 250mg Tablets
- if you know you are allergic to sulphonamides, sulphonamide derivatives including acetazolamide or to any of the ingredients in the medicine (listed in Section 6)
- if you have severe liver problems
- if you have or have ever had severe kidney problems
- if you have a particular type of glaucoma known as chronic non congestive angle closure glaucoma (your doctor will be able to advise you)
- if you have reduced function of the adrenal glands – glands above the kidneys – (also known as Addison's disease)
- if you have low blood levels of sodium and/or potassium or high blood levels of chlorine (your doctor will advise you). Speak to your doctor if any of the above applies to you. Warnings and precautions
Talk to your doctor or pharmacist before taking Diamox 250mg Tablets
- if you have or have ever had kidney problems such as kidney stones
- if you experienced lung or breathing problems such as fluid in the lungs or chronic bronchitis or emphysema, which cause difficulty in breathing following acetazolamide intake in the past.
- if you are over the age of 65
- a small number of people being treated with anti-epileptics such as Acetazolamide have had thoughts of harming or killing themselves, if at any time you have these thoughts, immediately contact your doctor. Diamox 250mg Tablets may affect some medical tests. If you visit a hospital or clinic for any medical tests, you should tell the doctor concerned that you are taking Diamox 250mg Tablets. If you develop shortness of breath or difficulty breathing after taking Diamox 250mg Tablets, seek medical attention immediately (see also section 4). A decrease in vision or eye pain could be symptoms of fluid accumulation in the vascular layer of the eye (choroidal effusion or choroidal detachment). This can happen within hours of taking Diamox 250mg Tablets. Talk to your doctor promptly if you experience these symptoms. Other medicines and Diamox 250mg Tablets Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines. The effects of any of these medicines may change, particularly if you are taking, or using, any of the following:
- medicines for your heart such as cardiac glycosides (e.g. digoxin)
- medicines to reduce blood pressure
- medicines to thin your blood (e.g. warfarin)
- medicines to lower the sugar in your blood (e.g. metformin, gliclazide)
- medicines for epilepsy or fits (in particular, phenytoin, primidone or carbamazepine or topiramate)
- Drugs which interfere with folic acid, e.g. methotrexate, pyrimethamine, or trimethoprim
- steroids such as prednisolone
- aspirin and related medicines, e.g. salicylic acid or choline salicylate for mouth ulcers
- other drugs in the group of medicines called carbonic anhydrase inhibitors (e.g. dorzolamide or brinzolamide which are also used to treat glaucoma)
- amphetamines (a stimulant), quinidine (treats an irregular heart beat), methenamine (prevents urine infections) or lithium (treats severe mental problems)
- sodium bicarbonate therapy (used to treat high states of acid in your body)
- ciclosporin (used to suppress the immune system). Pregnancy and breast feeding If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine. Pregnancy Diamox 250mg Tablets SHOULD NOT be taken if you are pregnant, think you are pregnant or are planning to become pregnant. Breast feeding It may be taken when breast feeding but only on the advice of the doctor.
Driving and using machines If Diamox 250mg Tablets make you feel drowsy or confused you should not drive or operate machines. Diamox 250mg Tablets can occasionally cause short-sightedness; if this happens and you feel that you can no longer drive safely, you should stop driving and contact your doctor. Information on Sodium content: This medicine contains less than 1 mmol sodium (23 mg) per dose, that is to say essentially 'sodium-free'.
How to take it
Diamox 250mg Tablets Always take this medicine exactly as your doctor or pharmacist has told you. Check with your doctor or pharmacist if you are not sure.
- This information will also be on the label.
- Diamox 250mg Tablets should be swallowed whole with a drink of water, just before or just after a meal. Do not chew or crush the tablets.
- The dose varies from person to person depending on their condition. Your doctor will decide on the most appropriate dose. If you are not sure how many tablets to take or when to take them, ask your doctor or pharmacist. The recommended dose is Glaucoma: Adults: 250mg-1000mg (1-4 tablets) every 24 hours, in divided doses. Retention of fluid: Adults: starting dose is 250-375mg (1-1.5 tablets) once daily in the morning. Your doctor will adjust the dose and tell you how often to take your dose. Epilepsy: Adults: 250-1000mg daily in divided doses. Children: the dose will depend on the bodyweight of the child, to be taken in divided doses. Dose should not be more than 750mg (3 tablets) per day.
- Before starting and during treatment your doctor may monitor your blood to check that treatment with Diamox 250mg Tablets is suitable for you.
If you take more Diamox 250mg Tablets than you should Get medical help immediately, either by calling your doctor or going to the nearest hospital casualty department. Take any remaining tablets and this leaflet with you so that the medical staff know exactly what you have taken. If you forget to take your Diamox 250mg Tablets You should take it as soon as you remember. However, if this is within two hours of your next dose you should skip the missed tablets and carry on taking the rest of your tablets as usual.
Do not take a double dose to make up for a forgotten dose. If you have any further questions on the use of this medicine, ask your doctor or pharmacist.
Possible side effects
Like all medicines, this medicine can cause side effects, although not everybody gets them. All medicines can cause allergic reactions although serious allergic reactions are very rare. Any sudden wheeziness, difficulty in breathing, swelling of the eyelids, face or lips, rash or itching (especially affecting your whole body) should be reported to a doctor immediately. Diamox 250mg Tablets can affect the cells in your blood. This could mean that you are more likely to catch infections and that your blood may not clot properly. If you have a sore throat or fever or you notice bruises or tiny red or purple spots on your skin you should contact your doctor immediately. If your muscles feel weak or you have fits, you should see your doctor immediately. Diamox 250mg Tablets can affect the liver and kidneys. If you experience pain in your lower back, pain or burning when you pass urine, have difficulty in passing urine, or you stop passing urine, have blood in your urine, pale stools, or if your skin or eyes look slightly yellow, you should contact your doctor. You should also contact your doctor if your stools are black or tarry, or if you notice blood in your stools. Contact a doctor immediately if you develop shortness of breath or difficulty breathing. These can be symptoms of accumulation of fluid in the lungs (pulmonary oedema). The frequency of this side effect cannot be estimated from the available data (not known). Not known: frequency cannot be estimated from the available data
- headache
- diarrhoea
- feeling or being sick, loss of appetite, thirst, or a metallic taste in the mouth
- dizziness, loss of full control of arms or legs
- looking flushed
- a need to pass urine more often than normal
- tiredness or irritability
- feeling over-excited
- a tingling or numbness in the fingers or toes, or coldness in the extremities.
- depression
- drowsiness or confusion
- a loss of interest in sex
- ringing in the ears or difficulty in hearing
- temporary short-sightedness which subsides when the dosage is reduced or treatment is stopped.
- Decrease in vision or pain in your eyes due to accumulation of fluid in the vascular layer of the eye (choroidal effusion or choroidal detachment). Rare cases of skin rashes including an increased sensitivity to sunlight have been reported. If you experience any unusual skin rashes, inform your doctor. If you take Diamox 250mg Tablets for a long time it can occasionally affect the amount of potassium, or sodium in your blood. Your doctor will probably take blood tests to check that this does not happen. You might also experience bone thinning or the risk of kidney stones with long-term therapy. High or low blood sugar levels may occasionally occur. Contact a doctor immediately if you experience a serious skin reaction: a red, scaly rash with bumps under the skin and blisters (exanthematous pustulosis). The frequency of this side effects is not known (cannot be estimated from the available data). If any of the side effects becomes serious, or if you notice any side effects not listed in this leaflet, please tell your doctor or pharmacist. Reporting of side effects If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine
How to store it
Diamox 250mg Tablets Do not store above 25°C. Store in the original pack or in containers which prevents the access of moisture. Keep this medicine out of the sight and reach of children. Do not use this medicine after the expiry date which is stated on carton. The Expiry date refers to last day of that month. Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines no longer use. These measures will help to protect the environment.
REMEMBER This medicine is for you. Only a doctor can prescribe it for you. Never give this medicine to someone else; it could harm them, even if their symptoms seem the same as yours.
Contents of the pack and other information
What Diamox 250mg Tablets Contain: The active substance is acetazolamide. Each tablet contains 250mg acetazolamide. The other ingredients are dicalcium phosphate, corn starch, magnesium stearate, sodium starch glycolate, povidone. What Diamox 250mg Tablets look like and contents of the pack: Diamox 250mg Tablets are white, circular shallow biconvex tablets with quarter breakline on one side and engraved "FW" and "147" on other side. They usually come in amber glass bottles with metal screw on caps or plastic bottles with plastic caps, containing 112 or 1000 tablets. Not all pack sizes may be marketed. Marketing Authorisation Holder: Mercury Pharmaceuticals Ltd., Dashwood House, 69 Old Broad Street, London, EC2M 1QS, United Kingdom Manufacturer: Custom Pharmaceuticals Limited, Conway Street, Hove, East Sussex, BN3 3LW, UK Skyepharma Production S.A.S., Zone Industrielle Chesnes Ouest, 55 rue du Montmurier, QUENTIN FALLAVIER, 38070, France
SAINT
This leaflet was last revised in October 2024. Mercury Pharma Group Ltd. is licensed to use the registered trademark Diamox 100105/LF/4
Frequently asked questions about Diamox 250mg Tablets
How do I take Diamox 250mg Tablets?
Diamox 250mg Tablets comes as tablet containing 250mg. Always follow the dose your doctor or pharmacist has given you, and read the leaflet that comes with the medicine.
What is the active substance in Diamox 250mg Tablets?
The active substance in Diamox 250mg Tablets is acetazolamide.
Are there equivalent medicines to Diamox 250mg Tablets?
Medicines with the same active substance, strength and form include: Acetazolamide 250 mg Tablet, Acetazolamide Mercury Pharma 250mg Tablets. They are interchangeable only if your prescriber or pharmacist says so.
Where does this information come from?
This leaflet reproduces the patient information leaflet approved for Diamox 250mg Tablets, as published on the electronic medicines compendium (emc). The version printed inside your medicine’s packaging is the one that applies to you.
Can I get Diamox 250mg Tablets without a prescription?
Whether a medicine is available over the counter or on prescription only depends on its licence. Check the leaflet, or ask your pharmacist — they can tell you straight away.
About this leaflet
The text above reproduces the patient information leaflet approved for this medicine, restructured for easier reading.
- Source: electronic medicines compendium (emc), Datapharm
- Active substance: acetazolamide
- Official document: view the original leaflet on emc →
⚕For healthcare professionals — Summary of Product Characteristics (SmPC)Full SmPC: dosage, interactions, contraindications, warnings+
4.1. Therapeutic indications
DIAMOX Tablets are for oral administration.
Acteazolamide is an enzyme inhibitor which acts specifically on carbonic anhydrase. It is indicated in the treatment of:
i)
Glaucoma: DIAMOX Tablets is useful in glaucoma (chronic simple (open angle) glaucoma, secondary glaucoma, and perioperatively in acute angle closure glaucoma where delay of surgery is desired in order to lower intraocular pressure) because it acts on inflow, decreasing the amount of aqueous secretion.
ii)
Abnormal retention of fluids: DIAMOX Tablets is a diuretic whose effect is due to the effect on the reversible hydration of carbon dioxide and dehydration of carbonic acid reaction in the kidney. The result is renal loss of HC03- ion which carries out sodium, water and potassium. DIAMOX Tablets can be used in conjunction with other diuretics when effects on several segments of the nepbron are desirable in the treatment of fluid retaining states.
iii)
Epilepsy: In conjunction with other anticonvulsants best results with DIAMOX Tablets have been seen in petit mal in children. Good results, however, have been seen in patients, both children and adults, with other types of seizures such as grand mal, mixed seizure patterns, myoclonic jerk patterns etc.
4.2. Posology and method of administration
Posology
i)
Glaucoma (simple acute congestive and secondary):
Adults: 250 - 1,000mg (1-4 tablets) per 24 hours, usually in divided doses for amounts over 250mg daily.
ii)
Abnormal retention of fluid: Congestive heart failure, drug-induced oedema.
Adults: For diuresis, the starting dose is usually 250 - 375mg (1-1½ tablets) once daily in the morning. If, after an initial response, the patient fails to continue to lose oedema fluid, do not increase the dose but allow for kidney recovery by omitting a day. Best results are often obtained on a regime of 250 - 375mg (1-1½ tablets) daily for two days, rest a day, and repeat, or merely giving the DIAMOX tablets every other day. The use of DIAMOX tablets does not eliminate the need for other therapy, eg. digitalis, bed rest and salt restriction in congestive heart failure and proper supplementation with elements such as potassium in drug-induced oedema.
For cases of fluid retention associated with pre-menstrual tension, a daily dose (single) of 125 - 375mg is suggested.
iii)
Epilepsy:
Adults: 250 - 1,000mg daily in divided doses.
Children: 8-30mg/kg in daily divided doses and not to exceed 750mg/day.
The change from other medication to DIAMOX tablets should be gradual.
Elderly: DIAMOX tablets should only be used with particular caution in elderly patients or those with potential obstruction in the urinary tract or with disorders rendering their electrolyte balance precarious or with liver dysfunction.
Method of administration:
Oral
4.3. Contraindications
Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.
Acetazolamide is contra-indicated in situations in which sodium and/or potassium blood levels are depressed, in cases of marked kidney and liver disease or dysfunction, suprarenal gland failure, and hyperchloremic acidosis. DIAMOX tablets should not be used in patients with hepatic cirrhosis as this may increase the risk of hepatic encephalopathy.
Long-term administration of DIAMOX tablets is contra-indicated in patients with chronic non-congestive angle-closure glaucoma since it may permit organic closure of the angle to occur while the worsening glaucoma is masked by lowered intraocular pressure.
DIAMOX tablets should not be used in patients hypersensitive to sulphonamides.
4.4. Special warnings and precautions for use
Suicidal ideation and behaviour have been reported in patients treated with anti-epileptic agents in several indications. A meta-analysis of randomised placebo controlled trials of anti-epileptic drugs has also shown a small increased risk of suicidal ideation and behaviour. The mechanism of this risk is not known and the available data do not exclude the possibility of an increased risk for Acetazolamide.
Therefore patients should be monitored for signs of suicidal ideation and behaviours and appropriate treatment should be considered. Patients (and caregivers of patients) should be advised to seek medical advice should signs of suicidal ideation or behaviour emerge.
Increasing the dose does not increase the diuresis and may increase the incidence of drowsiness and/or paraesthesia.
Increasing the dose often results in a decrease in diuresis. Under certain circumstances, however, very large doses have been given in conjunction with other diuretics in order to secure diuresis in complete refractory failure.
When DIAMOX tablets is prescribed for long-term therapy, special precautions are advisable. The patient should be cautioned to report any unusual skin rash. Periodic blood cell counts and electrolyte levels are recommended. Fatalities have occurred, although rarely, due to severe reactions to sulphonamides. A precipitous drop in formed blood cell elements or the appearance of toxic skin manifestations should call for immediate cessation of DIAMOX tablets therapy.
In patients with pulmonary obstruction or emphysema where alveolar ventilation may be impaired, DIAMOX tablets may aggravate acidosis and should be used with caution.
In patients with a past history of renal calculi, benefit should be balanced against the risks of precipitating further calculi.
The occurrence at the treatment initiation of a feverish generalized erythema associated with pustula may be a symptom of acute generalised exanthematous pustulosis (AGEP) (See section 4.8). In case of AGEP diagnosis, acetazolamide should be discontinued and any subsequent administration of acetazolamide contraindicated.
Non-cardiogenic pulmonary oedema
Severe cases of non-cardiogenic pulmonary oedema have been reported after taking acetazolamide, also after a single dose (see section 4.8). Non-cardiogenic pulmonary oedema typically developed within minutes to hours after acetazolamide intake. Symptoms included dyspnoea, hypoxia, and respiratory insufficiency. If non-cardiogenic pulmonary oedema is suspected, acetazolamide should be withdrawn, and supportive treatment should be given. Acetazolamide should not be administered to patients who previously experienced non-cardiogenic pulmonary oedema following acetazolamide intake.
Cases of choroidal effusion/detachment have been reported after the use of acetazolamide. Symptoms include acute onset of decreased visual acuity or ocular pain and can occur within hours after initiation of acetazolamide treatment. If choroidal effusion/detachment is suspected, acetazolamide should be discontinued as rapidly as possible.
Information on Sodium Content:
This medicine contains less than 1 mmol sodium (23 mg) per dose, that is to say essentially 'sodium-free'.
4.5. Interaction with other medicinal products and other forms of interaction
Acetazolamide is a sulphonamide derivative. Sulphonamides may potentiate the effects of folic acid antagonists. Possible potentiation of the effects of folic acid antagonists, hypoglycaemics and oral anti-coagulants may occur. Concurrent administration of acetazolamide and aspirin may result in severe acidosis and increase central nervous system toxicity. Adjustment of dose may be required when DIAMOX tablets is given with cardiac glycosides or hypertensive agents.
When given concomitantly, acetazolamide modifies the metabolism of phenytoin, leading to increased serum levels of phenytoin. Severe osteomalacia has been noted in a few patients taking acetazolamide in combination with other anticonvulsants. There have been isolated reports of reduced primidone and increased carbamazepine serum levels with concurrent administration of acetazolamide.
Because of possible additive effects, concomitant use with other carbonic anhydrase inhibitors is not advisable.
By increasing the pH of renal tubular urine, acetazolamide reduces the urinary excretion of amphetamine and quinidine and so may enhance the magnitude and the duration of effect of amphetamines and enhance the effect of quinidine.
Ciclosporin: Acetazolamide may elevate ciclosporin levels.
Methenamine: Acetazolamide may prevent the urinary antiseptic effect of methenamine.
Lithium: Acetazolamide increases lithium excretion and the blood lithium levels may be decreased.
Sodium bicarbonate: Acetazolamide and sodium bicarbonate used concurrently increases the risk of renal calculus formation.
4.6. Fertility, pregnancy and lactation
Pregnancy
Acetazolamide has been reported to be teratogenic and embryotoxic in rats, mice, hamsters and rabbits at oral or parenteral doses in excess of ten times those recommended in human beings. Although there is no evidence of these effects in human beings, there are no adequate and well-controlled studies in pregnant women. Therefore, Acetazolamide tablets should not be used in pregnancy, especially during the first trimester.
Breast-feeding
Acetazolamide has been detected in low levels in the milk of lactating women who have taken Acetazolamide tablets. Although it is unlikely that this will lead to any harmful effects in the infant, extreme caution should be exercised when Acetazolamide tablets is administered to lactating women.
Fertility
Not available
4.7. Effects on ability to drive and use machines
Increasing the dose does not increase the diuresis and may increase the incidence of drowsiness and/or paraesthesia. Less commonly, fatigue, dizziness and ataxia have been reported. Disorientation has been observed in a few patients with oedema due to hepatic cirrhosis. Such cases should be under close supervision. Transient myopia has been reported.
These conditions invariably subside upon diminution or discontinuance of the medication.
4.8. Undesirable effects
The following adverse reactions are classified by system organ class and ranked under heading of frequency using the following convention:
Not known: frequency cannot be estimated from the available data
System organ class
Frequency
Adverse reactions
Blood and lymphatic system disorders
Not known
Thrombocytopenia, Leukopenia, Aplastic anaemia, Bone marrow depression, Pancytopenia, Agranulocytosis****
Metabolism and nutrition disorder
Not known
Metabolic acidosis, electrolyte imbalance* and thirst**
Psychiatric disorders
Not known
Depression, Irritability, reduced libido, Occasional instances of confusion
Nervous system disorders
Not known
Paraesthesia, particularly a “tingling” feeling in the extremities, dizziness, Headache, Occasional instances of drowsiness, convulsions, Flaccid paralysis
Eye disorders
Not known
Transient myopia***
Choroidal effusion, choroidal detachment
Ear and labyrinth disorders
Not known
Impaired hearing and tinnitus
Respiratory, thoracic and mediastinal disorders
Not known
Non-cardiogenic pulmonary oedema
Gastrointestinal disorders
Not known
Melaena, Taste disturbance, Nausea, Vomiting Diarrhoea
Hepatobiliary disorders
Not known
Fulminant hepatic necrosis****, Hepatitis or cholestatic jaundice
Skin and subcutaneous tissue disorders
Not known
Urticaria, Rash (including Erythema multiforme, Stevens-Johnson syndrome, Toxic epidermal necrolysis)****, Thrombocytic purpura, Photosensitivity, acute generalised exanthematous pustulosis (AGEP)
Renal and urinary disorders
Not known
Haematuria, Crystalluria****, Renal and ureteral colic****, Renal lesions, Renal failure, Calculus formation****, Glycosuria, Polyuria
General disorders and administration site conditions
Not known
Fever****, Fatigue, Anaphylaxis****, Flushing
Investigations
Not known
Abnormal liver function
*During long-term therapy, metabolic acidosis and electrolyte imbalance may occasionally occur. This can usually be corrected by the administration of bicarbonate.
**Adverse reactions during short-term therapy are usually non-serious.
***This condition invariably subsides upon diminution or withdrawal of the medication.
****Acetazolamide is a sulphonamide derivative and therefore some side-effects similar to those caused by sulphonamides have occasionally been reported.
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
4.9. Overdose
No specific antidote. Supportive measures with correction of electrolyte and fluid balance. Force fluids.
💬 Ask about this leaflet
Ask anything about Diamox 250mg Tablets. The assistant answers only from this leaflet — if the leaflet does not cover it, it will say so. It does not give medical advice.
Answers come from the patient leaflet published on the electronic medicines compendium (emc). They are not medical advice. Ask a pharmacist or your GP if you are unsure. For urgent help call NHS 111, or 999 in an emergency.