While adverse reactions to Triamterene/HCTZ are uncommon, some patients who take the drug have been known to experience mild side effects, including frequent urination, headache, dizziness, lightheadedness, and upset stomach. Tell your doctor if any of these effects do not go away or are severe.
Rare, more serious adverse events have been known to occur. Get immediate medical attention if you experience any signs of an allergic reaction (rash, hives, itching, swelling, difficulty breathing or swallowing, etc); flu-like symptoms; changes to your heartbeat; yellowing of your skin or eyes; pain, swelling, or tenderness in your stomach; feelings of numbness, tingling, or burning on your skin.
Talk to your doctor about your medical history - particularly if you have or have had kidney stones, lupus, diabetes, gout, high potassium, or heart, thyroid, liver, or kidney disease. Inform your doctor of all known allergies and of all medications and supplements that you take. Tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding.
This is not a complete list of side effects or precautions. For more information please visit the National Institutes of Health’s DailyMed webpage for triamterene & hydrochlorothiazide.