Acetazolamide, Acetazolamide ER

Introduction

Written by Sarah Lewis, PharmD
Medically reviewed by Beth Thomas, PharmD
Updated on October 25, 2023

Acetazolamide (a set a ZOLE a mide) is a generic medication prescribed for fluid buildup and certain other conditions in adults. Acetazolamide belongs to a group of drugs called diuretics (water pills).

The Food and Drug Administration (FDA) has approved acetazolamide to:

• treat fluid buildup caused by certain drugs or congestive heart failure, along with other medications
• treat certain kinds of epilepsy, along with other medications
• treat glaucoma, along with other medications
• treat or help prevent symptoms of mountain sickness in climbers

These approved uses differ based on the form of acetazolamide your doctor prescribes.

This article doesn’t provide coupons for all forms of acetazolamide. To find coupons for acetazolamide extended-release oral capsule, see this article. 

Side effects of acetazolamide

Acetazolamide may cause mild or serious side effects. More common mild side effects of acetazolamide and its serious side effects are listed below. This article doesn’t include all possible side effects of the drug. Side effects can vary based on your age, overall health, and any other medications you take.

To learn more about acetazolamide’s side effects, ask your doctor or pharmacist. You can also refer to the prescribing information for acetazolamide listed in the “Resources” section.

Mild side effects

More common mild side effects reported with some forms of acetazolamide are listed below. These side effects may differ based on the form of acetazolamide you’re prescribed.

This article doesn’t include all possible mild side effects of the drug. To learn more about acetazolamide’s side effects based on the form, refer to the prescribing information for acetazolamide listed in the “Resources” section.

With many drugs, mild side effects may go away within a few days or a couple of weeks. If the side effects are bothersome, tell your doctor or pharmacist. They may be able to suggest ways to manage them.

Mild side effects of acetazolamide oral tablet and acetazolamide injection* include:

• diarrhea
• dizziness
• loss of appetite
• nausea or vomiting
• mild allergic reaction†

* Acetazolamide injection is given into a vein.
† For details about this side effect, see the “Interactions and warnings for acetazolamide” section.

Serious side effects

Serious side effects of acetazolamide are listed below. These side effects may differ based on the form of acetazolamide you’re prescribed.

This article doesn’t include all possible serious side effects of the drug. To learn more about acetazolamide’s side effects based on the form, refer to the prescribing information for acetazolamide listed in the “Resources” section.

With many drugs, serious side effects are possible but not common. If you have serious side effects from this drug, call your doctor right away. If you’re having severe symptoms or a medical emergency, call 911 or a local emergency number. 

In general, acetazolamide’s serious side effects include:

• balance or coordination problems
• changes in blood sugar levels
• changes in hearing or vision
• confusion
• convulsions (sudden, uncontrollable muscle movements)
• depression
• drowsiness or fatigue (low energy) that may affect your ability to drive or operate machinery
• electrolyte (mineral) imbalances
• kidney problems, including kidney failure
• liver problems, including liver failure
• loss of muscle tone resulting in weakness or paralysis
• metabolic acidosis (buildup of acid in the blood)
• low levels of blood cells, including white blood cells, red blood cells, and platelets
• skin sensitivity to sunlight, which may lead to sunburn
• severe allergic reaction*

* For details about this side effect, see the “Interactions and warnings for acetazolamide” section.

Uses of acetazolamide

The Food and Drug Administration (FDA) approves prescription drugs such as acetazolamide for certain conditions. Approved uses for acetazolamide are described below. These uses differ based on the form of acetazolamide prescribed.

Use for edema

Doctors may prescribe acetazolamide oral tablet or injection* for treating edema (fluid buildup). It’s used for this purpose in adults. It’s usually prescribed as a short-term treatment.

With edema, your body holds on to fluids, causing fluid buildup and swelling. It most often occurs in the lower legs, ankles, and feet. But it can also affect the hands and abdomen. Congestive heart failure is a common cause of edema. Certain medications can also cause it. Acetazolamide can help get rid of extra fluid in your body.

Acetazolamide is prescribed together with other medications for edema.

* Acetazolamide injection is given into a vein.

Use for certain kinds of epilepsy

Doctors may prescribe acetazolamide oral tablet or injection for treating certain kinds of epilepsy. It’s used for this purpose in adults. It’s usually prescribed as a short-term treatment, but sometimes doctors may prescribe it long term.

With epilepsy, you have an imbalance of electrical activity in your brain. This can cause seizures. Symptoms may include loss of consciousness, sudden rapid eye movements, and uncontrollable muscle spasms. Acetazolamide may lower the electrical activity in your brain that causes seizures.

Acetazolamide is prescribed together with other medications for seizures.

Use for glaucoma

Doctors may prescribe acetazolamide oral tablet, extended-release* oral capsule, or injection for treating glaucoma. It’s used for this purpose in adults. It’s usually prescribed as a short-term treatment.

With glaucoma, the pressure inside your eye is too high. This can damage the optic nerve and cause vision loss or blindness. (The optic nerve carries signals from the eye to the brain so you can see.) Acetazolamide can lower the pressure inside the eye and help prevent optic nerve damage.

Acetazolamide is prescribed together with other medications for glaucoma.

* With extended-release, the drug is released slowly over time in your body.

Use for mountain sickness

Doctors may prescribe acetazolamide oral tablet or injection to treat or help prevent mountain sickness. Doctors may also prescribe acetazolamide extended-release oral capsule to help prevent mountain sickness. It’s used for this purpose in adults. It’s usually prescribed as a short-term treatment.

With mountain sickness, climbers can develop serious symptoms from changes in altitude. It occurs because places that are very high above sea level have less oxygen in the air. Mountain sickness is more likely to happen when you climb to certain heights too quickly, without letting your body get used to the lower oxygen levels. Some people are also more sensitive to low-oxygen air. Mountain sickness can be fatal without quick treatment.

Symptoms can include confusion, dizziness, fatigue (low energy), headache, and nausea or vomiting. They can also include a fast heart rate, shortness of breath, trouble walking, and visual hallucinations (seeing things that aren’t really there). Acetazolamide works to lower symptoms of mountain sickness.

Common questions about acetazolamide

Below you’ll find answers to a few commonly asked questions about acetazolamide.

What is acetazolamide’s mechanism of action? How does the drug work? 

Acetazolamide is a diuretic drug (water pill). It works by helping your body get rid of fluid. It does this by blocking an enzyme (a type of protein) called carbonic anhydrase. This causes different effects in your body, such as:

• increasing the amount of urine your kidney makes
• lowering your eye pressure and the amount of fluid your eye makes
• reducing electrical activity in your brain that can cause seizures
• helping your body get used to low oxygen levels at high altitudes

Acetazolamide usually starts working within the first day of taking it. For mountain sickness, your doctor may recommend you take it a day or two before your climb to give it time to work.

If you’d like to know more about this, talk with your doctor or pharmacist. 

Is acetazolamide safe for older adults?

Possibly. This drug is approved for use in older adults (ages 65 years and older). But in studies* of acetazolamide oral tablet and injection,† there wasn’t enough evidence to know whether older adults respond differently than younger adults.

However, older adults often have reduced kidney function. This raises the risk of developing metabolic acidosis (a buildup of acid in the blood), a serious side effect of acetazolamide. Due to this risk, doctors usually start treatment with a lower dose in older adults.

If you have concerns about acetazolamide given your age, talk with your doctor.

* For details about the studies of acetazolamide oral tablet and injection, see its prescribing information in the “Resources” section.
† Acetazolamide injection is given into a vein.

Interactions and warnings for acetazolamide

Below, you’ll find information about acetazolamide’s possible interactions and warnings. 

Interactions of acetazolamide

Certain things may affect how a drug works. These include getting vaccines, consuming alcohol or certain foods, or taking the drug with other medications. This effect is called a drug interaction. 

Before you take acetazolamide, ask your doctor to check for possible interactions. Be sure to tell them about any of the following you take or use:

• prescription or over-the-counter drugs
• vitamins, herbs, or supplements

To learn about drug-condition interactions, see the “Warnings for acetazolamide” section below.

Warnings for acetazolamide

Some people should not take acetazolamide, and others should take it cautiously.

Acetazolamide could cause harm to people with certain health conditions. This effect is called a drug-condition interaction. Other factors can also affect whether acetazolamide is a safe option for you. 

Ask your doctor about specific warnings for acetazolamide, and be sure to tell your doctor about your:

• current health, including any allergies to medications
• past health conditions or surgeries

Allergic reaction

Acetazolamide can cause an allergic reaction in some people. Severe allergic reactions are rare but possible.

If you’ve had an allergic reaction to acetazolamide or any of its ingredients, your doctor will likely not prescribe acetazolamide. They can tell you about medications that are safer options for you.

A mild allergic reaction may cause the following symptoms:

• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)

A severe allergic reaction may cause the following symptoms:

• severe skin rashes that may blister and peel
• swelling under your skin, usually in your hands, feet, eyelids, or lips
• swelling of your mouth, throat, or tongue, which can cause breathing problems 

If you have an allergic reaction to acetazolamide, call your doctor right away. If you have severe symptoms, call 911 or a local emergency number.

Overdose of acetazolamide

If you take acetazolamide by mouth, you should not take more acetazolamide than your doctor prescribes. For some drugs, doing so may lead to harmful effects or overdose.

If you think you’ve taken too much acetazolamide, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have concerning symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.

Pregnancy or breastfeeding and acetazolamide

Information about acetazolamide and pregnancy and breastfeeding is described below.

Acetazolamide and pregnancy

It’s not known whether acetazolamide should be taken during pregnancy. If you’re planning a pregnancy or can become pregnant, talk with your doctor before taking this medication. 

Acetazolamide and breastfeeding

Acetazolamide should not be taken while breastfeeding. If you’re currently breastfeeding or planning to do so, talk with your doctor before taking this medication. Your doctor may recommend other ways to feed your child during treatment with acetazolamide. 

What to ask your doctor

Let your doctor know if you have questions about acetazolamide or would like more details about it.

Here’s a list of some possible questions you may want to ask your doctor:

• How long is it safe to take acetazolamide?
• How does acetazolamide compare to other medications that could treat my condition?
• What’s the most important information I should know about acetazolamide?

Resources

• Acetazolamide extended-release capsules. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/e8e48a25-5f6c-4b5a-a5f2-ee87aabea33b/spl-doc 
• Acetazolamide for injection USP. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/4dd56001-4941-4ff0-9f30-02a1bcc4fe7e/spl-doc 
• Acetazolamide tablets, USP. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/ddfd44dc-3136-4dda-8ed0-eb2991c2a0b6/spl-doc 
• Food and Drug Administration. (2023). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.