SIDE EFFECTS: See also Warning section. Dizziness, lightheadedness, tiredness, headache, stomach upset, or diarrhea may 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 this medication has been prescribed because your doctor 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. Triamterene can cause dehydration and electrolytes imbalance. Tell your doctor right away if you have any symptoms of dehydration or electrolytes imbalance, such as confusion, unusual dry mouth/thirst, fast/irregular heartbeat, severe dizziness/lightheadedness, or seizures. Tell your doctor right away if you have any serious side effects, including: nausea/vomiting that doesn't stop, stomach/abdominal pain, yellowing eyes/skin, dark urine, signs of infection (such as sore throat that doesn't go away, fever, chills, cough), signs of kidney problems (such as pain in the side/back/abdomen, painful urination, blood in the urine, change in the amount of urine), joint pain (such as big toe pain), easy bruising/bleeding. 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.

HOW TO USE: Take this medication by mouth as directed by your doctor, usually once or twice a day after a meal. If you take this drug too close to bedtime, you may need to wake up to urinate. It is best to take this medication at least 4 hours before your bedtime. To reduce your risk of side effects, your doctor may direct you to start this medication at a low dose and gradually increase your dose. Follow your doctor's instructions carefully. The dosage is based on your medical condition and response to treatment. Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time(s) each day. 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. Do not stop taking this medication without consulting your doctor. Some conditions may become worse when this drug is suddenly stopped. Your dose may need to be gradually decreased. Tell your doctor if you do not get better or if you get worse.

PRECAUTIONS: See also Warning section. Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney problems (such as kidney stones), liver disease, mineral imbalance (such as high potassium blood level, low sodium blood level), dehydration, gout, conditions causing low folic acid blood levels (such as alcoholic cirrhosis, pregnancy). This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis). If you have diabetes, triamterene may affect your blood sugar. Check your blood sugar regularly as directed and share the results with your doctor. Tell your doctor right away if you have symptoms of high blood sugar such as increased thirst/urination. Your doctor may need to adjust your diabetes medication, exercise program, or diet. Severe sweating, diarrhea, or vomiting can increase the risk for dehydration. Report prolonged diarrhea or vomiting to your doctor. To prevent dehydration, drink plenty of fluids unless your doctor directs you otherwise. This medication may increase your potassium levels. Before using potassium supplements or salt substitutes that contain potassium, consult your doctor or pharmacist. 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. Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). Older adults may be more sensitive to the side effects of this drug, especially high potassium blood levels. During pregnancy, this medication should be used only when clearly needed. It may harm an unborn baby. Discuss the risks and benefits with your doctor. This drug may pass into breast milk. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: See also Precautions section. 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: drugs that may increase the level of potassium in the blood (such as amiloride, cyclosporine, eplerenone, tacrolimus, birth control pills containing drospirenone), lithium. Some products have ingredients that could raise your blood pressure or worsen your swelling. Tell your pharmacist what products you are using, and ask how to use them safely (especially cough-and-cold products, diet aids, or 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.

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. Symptoms of overdose may include: severe dizziness, muscle weakness, slow/irregular heartbeat.