Uses

What is acetazolamide used for?

Acetazolamide is commonly used for the following conditions.

Acetazolamide may also be used for other conditions as determined by your healthcare provider. 

How does acetazolamide work (mechanism of action)?

Acetazolamide blocks an enzyme called carbonic anhydrase in the body. This helps lower pressure inside the eye, increases how much you pee to treat fluid retention, decreases seizures, and improves symptoms of altitude sickness. 

How is acetazolamide supplied (dosage forms)?

Acetazolamide is available in the following dosage forms that are taken by mouth.

  • 500 mg extended-release oral capsules
  • 125 mg oral tablets
  • 250 mg oral tablets 

Acetazolamide is also available in injectable forms.

How should I store acetazolamide?

Acetazolamide should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place in a tightly closed container.

Side Effects

What are the most common side effects of acetazolamide?

The most common side effects of acetazolamide are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Headache
  • General feeling of being unwell, tired, or not having your usual energy
  • Tiredness or drowsiness
  • Fever
  • Nausea, vomiting, or diarrhea
  • Loss of appetite
  • Change in how things taste
  • Needing to pee much more often than usual
  • Numbness, tingling, or burning sensation in your arms, feet, or face 
  • Depression
  • Trouble with balance or coordination
  • Confusion
  • Dizziness
  • Trouble hearing or hearing a ringing or buzzing sound in your ears
  • Trouble seeing faraway objects 
  • Pain at the injection site (injection)

There may be other side effects of acetazolamide that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of acetazolamide?

While less common, the most serious side effects of acetazolamide are described below, along with what to do if they happen.

Severe Allergic Reactions. Acetazolamide may cause allergic reactions, which can be serious. Stop taking acetazolamide and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Severe Skin Reactions. Acetazolamide can cause severe skin reactions, called Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN), that can lead to death if not treated. If you develop a rash, stop acetazolamide and call your healthcare provider right away. Get emergency help right away if you have any of the following symptoms of SJS or TEN.

  • Painful red or purple skin that looks burned and peels off
  • Flat red rash or blisters on your skin, mouth, nose, and genitals
  • Red, painful, watery eyes

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking acetazolamide. Call your healthcare provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine (pee)
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Blood Disorders. Acetazolamide can cause blood disorders, such as agranulocytosis, aplastic anemia, hemolytic anemia, and low white blood cell levels (leukopenia). Stop taking acetazolamide and get help right away if you have any of the following symptoms of blood disorders.

  • Fever
  • Shortness of breath
  • Pale or yellowish skin
  • Easy bruising or bleeding
  • Frequent infection
  • Unusual weakness or tiredness
  • Dizziness, lightheadedness, or feeling like you are about to pass out
  • Headache
  • Fast or abnormal heartbeat

Kidney Stones. Acetazolamide may cause kidney stones. Drinking plenty of water can help prevent kidney stones. Tell your healthcare provider right away if you develop severe pain in your side or back or have blood in your urine (pee). Your pee may look pink, red, or brown.

Metabolic Acidosis. Acetazolamide can cause or worsen a condition called metabolic acidosis. Metabolic acidosis happens when there is too much acid in the blood. If this condition is not treated, it can cause kidney stones, slowed growth in children, your bones can become soft or brittle (osteoporosis, osteomalacia (rickets), osteopenia), or cause harm to your unborn baby if you are pregnant. Tell your healthcare provider right away if you have any of the following symptoms of metabolic acidosis.

  • Fast breathing or heartbeat
  • Headache
  • Feeling confused, weak, or tired
  • Not feeling hungry
  • Nausea or vomiting

Electrolyte Changes. Acetazolamide may cause changes to the levels of certain minerals in your body, called electrolytes. For example, it may cause low potassium levels (hypokalemia) or low sodium levels (hyponatremia). These changes can be serious. Keep appointments for blood work so that your healthcare provider can check your electrolyte levels, especially if you take certain other medicines. Call your healthcare provider if you have any of the following symptoms of electrolyte changes.

  • Weakness
  • Unusual tiredness
  • Muscle cramps or twitching
  • Constipation
  • Nausea, vomiting, or loss of appetite
  • Dizziness
  • Restlessness or irritability
  • Difficulty breathing
  • Confusion or decreased alertness

High or Low Blood Sugar (Hyperglycemia or Hypoglycemia). Acetazolamide can cause high or low blood sugar. If you have diabetes, you may need to check your blood sugar more often if you have changes to your diet, exercise regimen, or medicines for diabetes. Do not take acetazolamide and call your healthcare provider right away if you have any of the following symptoms of hypoglycemia.

  • Headache
  • Crankiness or anxiety
  • Hunger
  • Dizziness or confusion
  • Blurry vision
  • Slurred speech
  • Sweating
  • Feeling jittery or shakiness
  • Fast heartbeat
  • Seizures

Warnings & Precautions

Who should not use acetazolamide?

Allergies to Ingredients. People who are allergic to any of the following should not take acetazolamide.

  • Acetazolamide
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific acetazolamide products they stock.

Sulfa Allergy. Some people who have a sulfa allergy may also be allergic to acetazolamide. A sulfa allergy is a rash or more serious reaction to sulfa, or sulfonamide, medicines. Sulfa medicines include sulfamethoxazole, sulfadiazine silver, or sulfasalazine. Tell your healthcare provider if you have any allergies to medicines. Your healthcare provider can help you decide if it is safe for you to take acetazolamide.

Kidney Problems. Acetazolamide should not be taken if your kidneys are not working as well as they should be. If there is a concern about the health of your kidneys, your healthcare provider may do tests to determine if they are working well enough to take this medicine.

Liver Problems. Acetazolamide should not be taken if your liver is not working as well as it should be. If there is a concern about the health of your liver, your healthcare provider may do tests to determine if it is working well enough to take this medicine.

Adrenal Gland Failure. Do not take acetazolamide if you have adrenal gland failure, which is when your body’s adrenal glands are not able to make enough cortisol (a stress hormone). 

Hyperchloremic Acidosis. Do not take acetazolamide if you have hyperchloremic acidosis. This is a condition caused by low levels of bicarbonate and high levels of chloride in the blood. This causes the blood to become too acidic. Your healthcare provider may do blood work to see if it is safe for you to take this medicine. 

Angle-closure Glaucoma. Do not take acetazolamide for a long period of time if you have a certain type of glaucoma called angle-closure glaucoma. Angle-closure glaucoma is an eye condition where fluid buildup rapidly increases pressure inside the eye. This can cause sudden vision problems and pain. Ask your healthcare provider if you are not sure what type of glaucoma you have and whether it is safe for you to take acetazolamide. 

Low Sodium Level (Hyponatremia). Do not take acetazolamide if you have low sodium levels. Your healthcare provider may use lab tests to check your sodium levels to determine if the levels are safe to take this medicine. 

Low Potassium Level (Hypokalemia). Do not take acetazolamide if you have low potassium levels. Your healthcare provider may use lab tests to check your potassium levels to determine if the levels are safe to take this medicine. 

What should I know about acetazolamide before using it?

Do not take acetazolamide unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share acetazolamide with other people, even if they have the same condition as you. It may harm them.

Keep acetazolamide out of the reach of children.

Acetazolamide can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how acetazolamide affects you.

People who are 65 and older can be at greater risk for some side effects from acetazolamide. Talk to your healthcare provider about your risks if you are in this age group.

Acetazolamide can make your skin more sensitive to light from the sun, sunlamps, and tanning beds. This is called photosensitivity. Exposure to this light can cause severe sunburns, blisters, and swelling. If you need to be in sunlight, wear sunscreen, a hat, and clothing that covers your skin.

If you are taking acetazolamide for altitude sickness, watch for symptoms such as confusion, shortness of breath even at rest, an inability to walk, a cough that produces a white or pink frothy substance, or coma. These could be symptoms of severe altitude sickness. You may need to descend rapidly if you have these symptoms.

What should I tell my healthcare provider before using acetazolamide?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if acetazolamide is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • Diabetes
  • Lung problems
  • Liver problems
  • Kidney problems
  • Low sodium level (hyponatremia) 
  • Low potassium level (hypokalemia) 

FD&C Yellow No. 6 Sensitivity. Acetazolamide extended-release capsules contain FD&C Yellow No. 6, which may cause an allergic reaction if you are sensitive to this dye. People with a severe allergic reaction to aspirin are more likely to be sensitive to FD&C Yellow No. 6. Tell your healthcare provider if you are allergic to FD&C Yellow No. 6, aspirin, or any other medicines. Your healthcare provider can help you decide if it is safe for you to take acetazolamide.

Other Medicines and Supplements. Acetazolamide may interact with other medicines and supplements. Before taking acetazolamide, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how acetazolamide could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. 

Breastfeeding. It is not known if acetazolamide passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take acetazolamide while breastfeeding.

Interactions

Does acetazolamide interact with foods or drinks?

There are no known interactions between acetazolamide and foods or drinks.

It is unknown if drinking alcohol will affect acetazolamide. The risk of dizziness or drowsiness may be increased if you drink alcohol while taking acetazolamide.

Does acetazolamide interact with other medicines (drug interactions)?

Acetazolamide interacts with many other medicines. Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking acetazolamide.

  • Aspirin, which is in many prescription and OTC products including those for pain, swelling, and fever
  • Phenytoin (Dilantin, Phenytek, and others), which is a medicine to control seizures
  • Primidone (Mysoline), which is a medicine to control seizures
  • Any other carbonic anhydrase inhibitor, such as zonisamide (Zonegran and others) or methazolamide, which are used to control seizures or treat glaucoma 
  • A folic acid antagonist, such as methotrexate (Trexall, Jylamvo, and others), pyrimethamine (Daraprim), trimethoprim, or sulfasalazine (Azulfidine), which are medicines used for a variety of conditions
  • A medicine for diabetes
  • An amphetamine, which is a medicine to treat attention deficit hyperactivity disorder or narcolepsy
  • Quinidine, which is a medicine used to control heart rate or rhythm (antiarrhythmic)
  • Methenamine, which is a medicine used to prevent repeated kidney or bladder infections
  • Lithium, which is a medicine for certain mental health conditions
  • Sodium bicarbonate, which is a medicine for heartburn and upset stomach
  • Cyclosporine (Gengraf, Neoral, Sandimmune, and others), which is a medicine that suppresses the immune system

This may not be a complete list of medicines that can interact with acetazolamide. Always check with your healthcare provider.

Does Acetazolamide interact with other drugs you are taking?
Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much acetazolamide?

If you or someone else has used too much acetazolamide, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of acetazolamide?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.

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