Acetazolamide belongs to the class of medications called carbonic anhydrase inhibitors. It is used to reduce the pressure in the eye for people with certain types of glaucoma. It is also sometimes used to treat epilepsy. It may also be used in the treatment of certain cases of salicylate overdosage.

Fluid is constantly being formed and drained out of the eye. When this fluid does not drain out of the eye properly or too much fluid is produced, the pressure inside the eye increases. Acetazolamide works by reducing the amount of fluid produced by the eye and central nervous system. Its effects on the central nervous system are also believed to help treat some forms of epilepsy that are caused by higher fluid levels in the central nervous system. Acetazolamide decreases the acidity of the urine, increasing the amount of salicylate passed out of the body through the kidneys.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

Recommended doses of acetazolamide vary depending on the condition being treated and the circumstances.

For glaucoma, the usual recommended dose is 250 mg by mouth 1 to 4 times a day. For some types of glaucoma, the dosage may be 250 mg every 4 hours.

For epilepsy, the usual recommended dose is 375 mg to 1,000 mg daily by mouth, usually in divided doses so that it's taken 1 to 4 times a day.

To decrease urine acidity, the recommended dose is 250 mg taken every 4 to 6 hours.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor.

If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Each white, round, biconvex tablet, cross-scored on one side and engraved "250" on the other side contains acetazolamide 250 mg. Nonmedicinal ingredients: colloidal silicon dioxide, magnesium stearate, and microcrystalline cellulose.

Do not take acetazolamide if you:

• are allergic to acetazolamide or any ingredients of the medication
• have low levels of sodium or potassium in your blood
• have severe kidney or liver dysfunction
• have increased levels of acid in the blood
• have decreased adrenal gland function
• have severe glaucoma or hemorrhagic glaucoma

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• confusion
• drowsiness
• increased sensitivity to the sun
• increased urination
• loss of appetite
• malaise (generally feeling of discomfort)
• metallic taste
• muscle weakness
• nausea or vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• dark-coloured stools
• fever
• hives
• increased frequency of infections (e.g., fever, chills, sore throat, mouth ulcers)
• rash
• ringing in ears or hearing loss

• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding, red or purple spots on the skin)
• signs of kidney problems (e.g., decreased urination, nausea, vomiting, swelling of the feet and ankles, blood in the urine)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• tingling feeling in fingers and toes

Stop taking the medication and seek immediate medical attention if any of the following side effects occur:

• seizures
• signs of an allergic reaction (e.g., wheezing, tightness in chest, troubled breathing, shortness of breath, or cough)
• signs of severe skin reactions (e.g., blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Allergies: Some people who are allergic to a group of medications called sulfonamides may experience a reaction to acetazolamide. If you have a known sulfonamide allergy, your doctor may monitor you for any allergic reactions.

Blood tests: Your doctor may recommend you get lab tests to check your blood at regular intervals while you are taking acetazolamide.

Diabetes: Acetazolamide may increase blood sugar or urine sugar levels. If you have diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Drowsiness/reduced alertness: This medication may make you drowsy. Do not drive or engage in other activities requiring alertness if the medication affects you in this way.

Lungs: If you have certain lung problems, your doctor will closely monitor your condition while you are taking acetazolamide, as it may affect the amount of oxygen in your body.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are breast-feeding and taking acetazolamide, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

Seniors: People over the age of 65 may be more at risk of side effects from this medication.

For a full list of interactions, use the Drug Interaction Checker available on the Drugs.com website.

If you are taking other medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.