SIDE EFFECTS: 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, stomach upset, headache and tiredness may also occur. If any of these symptoms persist or worsen, notify your doctor or pharmacist. 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 any of these very unlikely but serious side effects occur: increased body hair, hearing loss, ringing in the ears, unusual tiredness, persistent nausea/vomiting, severe stomach/abdominal pain. Seek immediate medical attention if any of these unlikely but very serious side effects occur: easy bleeding/bruising, fast/irregular heartbeat, signs of infection (e.g., fever, persistent sore throat), mental/mood changes (e.g., confusion, difficulty concentrating), severe muscle cramps/pain, tingling of the hands/feet, blood in the urine, dark urine, painful urination, yellowing of the eyes/skin. A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include: blisters/sores in the mouth, 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.

PRECAUTIONS: Before taking acetazolamide, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: adrenal gland problems (e.g., Addison's disease), low blood levels of sodium or potassium, severe kidney disease, severe liver disease (e.g., cirrhosis), certain metabolic problems (e.g., hyperchloremic acidosis). Before using this medication, tell your doctor or pharmacist your medical history, especially of: breathing problems (e.g., emphysema, chronic bronchitis), high levels of calcium, dehydration, diabetes mellitus, gout, narrow-angle glaucoma, overactive thyroid (hyperthyroidism). While this medication can help you get used to high altitudes and help you tolerate quick climbs, it cannot completely prevent serious altitude sickness. Symptoms of serious altitude sickness may include: severe shortness of breath, mental/mood changes (e.g., confusion, difficulty concentrating), lack of coordination/staggering walk, extreme tiredness, severe headache. If you develop any of these symptoms, it is very important that you descend to a lower altitude as quickly as possible to prevent serious, possibly fatal problems. This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana. To minimize dizziness and lightheadedness, get up slowly when rising from a seated or lying position. This drug may rarely make your blood sugar rise, which can cause or worsen diabetes. Tell your doctor right away if you have symptoms of high blood sugar such as increased thirst/urination. If you already have diabetes, check your blood sugar regularly as directed and share the results with your doctor. This medication may also lower your blood sugar. Symptoms of low blood sugar include sudden sweating, shaking, fast heartbeat, hunger, blurred vision, dizziness or tingling hands/feet. It is a good habit to carry glucose tablets or gel to treat low blood sugar. If you don't have these reliable forms of glucose, rapidly raise your blood sugar by eating a quick source of sugar such as table sugar, honey, or candy, or by drinking a glass of orange juice or non-diet soda. Tell your doctor right away about the reaction and the use of this product. To help prevent low blood sugar, eat meals on a regular schedule, and do not skip meals. This medication may make you more sensitive to the sun. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your doctor right away if you get sunburned or have skin blisters/redness. This medication should not be used in children less than 12 because it may affect normal growth. This medication should be used with caution in the elderly because they may be more sensitive to its side effects, especially low potassium or sodium levels. This medication should be used during pregnancy only if clearly needed. Discuss the risks and benefits with your doctor. This medication passes into breast milk but is unlikely to harm a nursing infant. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: 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, methenamine, anticonvulsants (e.g., phenytoin, topiramate, zonisamide), digoxin, drugs that cause loss of potassium (e.g., diuretics such as furosemide, corticosteroids such as prednisone, amphotericin B), lithium, memantine, orlistat, quinidine, salicylates (e.g., aspirin, bismuth subsalicylate), sodium bicarbonate, tricyclic antidepressants (e.g., amitriptyline). Check all prescription and nonprescription labels carefully since they may contain medications (e.g., anti-diarrhea drugs, pain relievers/fever reducers) similar to aspirin, which can cause serious side effects when taken with acetazolamide. Low-dose aspirin, as prescribed by your doctor for specific medical reasons such as heart attack or stroke prevention (usually at dosages of 81-325 milligrams per day), should be continued. Consult 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 laboratory tests, possibly causing false test results. Make sure laboratory personnel and your doctor know you use this drug.

OVERDOSE: 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.