Acetazolamide is used to prevent and reduce the symptoms of altitude sickness. This medication can decrease headache, tiredness, nausea, dizziness, and shortness of breath that can occur when you climb quickly to high altitudes (generally above 10,000 feet/3,048 meters). It is particularly useful in situations when you cannot make a slow ascent. The best ways to prevent altitude sickness are climbing slowly, stopping for 24 hours during the climb to allow the body to adjust to the new height, and taking it easy the first 1 to 2 days. This medication is also used with other medications to treat high pressure inside the eye due to certain types of glaucoma. Acetazolamide belongs to a class of drugs known as carbonic anhydrase inhibitors. It works by decreasing the production of fluid inside the eye. It is also used to decrease a buildup of body fluids (edema) caused by heart failure or certain medications. Acetazolamide can work less well over time, so it is usually used only for a short period. It has also been used with other medications to treat certain types of seizures (petit mal and unlocalized seizures).
If you are taking the tablets, take this medication by mouth as directed by your doctor, usually 1 to 4 times daily. If you are taking the long-acting capsules, take this medication by mouth as directed by your doctor, usually 1 or 2 times daily. Swallow the long-acting capsules whole. Do not open, break, or chew the capsules. Doing so can destroy the long action of the drug and may increase side effects. Acetazolamide may be taken with or without food. Drink plenty of fluids unless otherwise directed by your doctor. The dosage is based on your medical condition and response to treatment. To prevent altitude sickness, start taking acetazolamide 1 to 2 days before you start to climb. Continue taking it while you are climbing and for at least 48 hours after you have reached your final altitude. You may need to continue taking this medication while staying at the high altitude to control your symptoms. If you develop severe altitude sickness, it is important that you climb down as quickly as possible. Acetazolamide will not protect you from the serious effects of severe altitude sickness. (See also Precautions.) If you are taking this drug for another condition (such as glaucoma, seizures), use this medication regularly as directed to get the most benefit from it. To help you remember, take it at the same time(s) each day. Taking your last dose in the early evening will help prevent you from having to get up in the middle of the night to urinate. Consult your doctor or pharmacist if you have questions about your dosing schedule. Do not increase your dose or use this drug more often or for longer than prescribed. Your condition will not improve any faster, and your risk of side effects will increase. When used for an extended period, this medication may not work as well and may require different dosing. Your doctor will be monitoring your condition. Tell your doctor if your condition does not improve or if it worsens (for example, you have more frequent seizures). This drug may reduce the potassium levels in your blood. Your doctor may recommend that you eat foods rich in potassium (such as bananas or orange juice) while you are taking this medication. Your doctor may also prescribe a potassium supplement for you to take during treatment. Consult your doctor for more information. Tell your doctor if your condition lasts or gets worse.
Dizziness, lightheadedness, or increased urination may occur, especially during the first few days as your body adjusts to the medication. Blurred vision, dry mouth, drowsiness, loss of appetite, nausea, vomiting, diarrhea, or changes in taste may also occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly. To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: tingling of the hands/feet, hearing loss, ringing in the ears, unusual tiredness, easy bleeding/bruising, fast/irregular heartbeat, muscle cramps/pain, mental/mood changes (such as confusion, difficulty concentrating), signs of liver disease (such as nausea/vomiting that doesn't stop, stomach/abdominal pain, yellowing eyes/skin, dark urine), signs of kidney problems (such as painful urination, pink/bloody urine, change in the amount of urine), signs of infection (such as sore throat that doesn't go away, fever, chills). A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets. Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval. Some products that may interact with this drug include: cisapride, lithium, memantine, methenamine, orlistat, certain drugs used to treat seizures (topiramate, zonisamide). Check the labels on all your medicines because they may contain aspirin or aspirin-like drugs (salicylates), which can cause serious side effects if taken in large doses with this medication. However, if your doctor has directed you to take low-dose aspirin for heart attack or stroke prevention (usually at dosages of 81-325 milligrams a day), you should continue taking it unless your doctor instructs you otherwise. Ask your doctor or pharmacist for more details. Some products have ingredients that could worsen your swelling. Tell your pharmacist what products you are using, and ask how to use them safely (especially NSAIDs such as ibuprofen/naproxen). This medication may interfere with certain lab tests, possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.
If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.