Side Effects of Dyazide (triamterene and hydrochlorothiazide)

Dyazide (triamterene and hydrochlorothiazide) is a combination of two different diuretics (water pills) used to treat high blood pressure (hypertension) and fluid retention (edema).

Diuretics eliminate salt (sodium) and water from the body. Hydrochlorothiazide can be used alone for treating high blood pressure and edema.

• It works by blocking sodium and water reabsorption in the kidneys, thereby reducing sodium and water in the body.
• To compensate for the increased amount of sodium and water in the tubules that will be lost as urine, the kidney tries to reabsorb more sodium and water.
• It does this by removing potassium from the blood and putting it into the tubules in exchange for sodium (and water) in the tubules.
• As a result, blood potassium levels fall.
• Triamterene prevents reabsorption of sodium in exchange for potassium.
• Thus, it reduces sodium and water in the body but also prevents the depletion of potassium.
• By combining hydrochlorothiazide with triamterene, sodium and water are eliminated from the body without the loss of potassium.
• However, Dyazide may allow potassium levels to increase so potassium levels should be closely monitored. 

Common side effects of Dyazide include

• abdominal pain,
• nausea,
• vomiting,
• rash,
• headache,
• dizziness,
• constipation,
• low blood pressure,
• electrolyte disturbance (for example, high potassium levels),
• muscle cramps,
• hypersensitivity, and
• yellowing skin and eyes (jaundice). 

Serious side effects of Dyazide include

• pancreatitis and
• increased blood sugar (glucose) levels and worsening diabetes.

Patients allergic to sulfa drugs may also be allergic to hydrochlorothiazide because of the similarity in the chemical structure of the two drugs.

Drug interactions of Dyazide include ACE inhibitors, aliskiren, eplerenone, potassium supplements or other drugs that also increase potassium, when taken with Dyazide, may lead to dangerous potassium levels in the body.

Salt substitutes (for example, Mrs. Dash) contain potassium and may lead to excessive potassium levels in the body if combined with Dyazide.

Hydrochlorothiazide increases adverse effects of dofetilide. Hydrochlorothiazide reduces the elimination of lithium by the kidneys, increasing lithium toxicity.

Nonsteroidal anti-inflammatory drugs may reduce the blood pressure-reducing effects of Dyazide.

Combining hydrochlorothiazide with corticosteroids may increase the risk for low levels of blood potassium and other electrolytes.

Low blood potassium can increase the toxicity of digoxin.

Cholestyramine and colestipol bind to hydrochlorothiazide and reduce its absorption from the gastrointestinal tract.

Blood sugar levels can be elevated by hydrochlorothiazide requiring adjustment in the doses of medications used to treat diabetes.

Dyazide has not been adequately studied in pregnant women. Dyazide has not been evaluated in nursing mothers. Hydrochlorothiazide is excreted in breast milk. Intense diuresis using hydrochlorothiazide may reduce the production of breast milk. Otherwise, hydrochlorothiazide is considered safe to use during nursing if required by the mother. Consult your doctor before breastfeeding.

Common side effects of Dyazide include

• dizziness,
• lightheadedness,
• headache, or
• upset stomach as your body adjusts to the medication.

Other side effects of Dyazide include

• nausea,
• diarrhea,
• constipation,
• blurred vision,
• dry mouth, or
• skin rash.

Adverse effects are listed in decreasing order of severity.

Hypersensitivity: Anaphylaxis, rash, urticaria, subacute cutaneous lupus erythematosus-like reactions, photosensitivity.

Cardiovascular: Arrhythmia, postural hypotension.

Metabolic: Diabetes mellitus, hyperkalemia, hypokalemia, hyponatremia, acidosis, hypercalcemia, hyperglycemia, glycosuria, hyperuricemia, hypochloremia.

Gastrointestinal: Jaundice and/or liver enzyme abnormalities, pancreatitis, nausea and vomiting, diarrhea, constipation, abdominal pain.

Renal: Acute renal failure (one case of irreversible renal failure has been reported), interstitial nephritis, renal stones composed primarily of triamterene, elevated BUN, and serum creatinine, abnormal urinary sediment.

Hematologic: Leukopenia, thrombocytopenia and purpura, megaloblastic anemia.

Musculoskeletal: Muscle cramps.

Central Nervous System: Weakness, fatigue, dizziness, headache, dry mouth.

Miscellaneous: Impotence, sialadenitis.

Thiazides alone have been shown to cause the following additional adverse reactions:

Central Nervous System: Paresthesias, vertigo.

Ophthalmic: Xanthopsia, transient blurred vision.

Respiratory: Allergic pneumonitis, pulmonary edema, respiratory distress.

Other: Necrotizing vasculitis, exacerbation of lupus.

Hematologic: Aplastic anemia, agranulocytosis, hemolytic anemia.

Neonate and infancy: Thrombocytopenia and pancreatitis-rarely, in newborns whose mothers have received thiazides during pregnancy.

Skin: Erythema multiforme including Stevens-Johnson syndrome, exfoliative dermatitis including toxic epidermal necrolysis.

Angiotensin-converting Enzyme Inhibitors: Potassium-sparing agents should be used with caution in conjunction with angiotensin-converting enzyme (ACE) inhibitors due to an increased risk of hyperkalemia.

Oral Hypoglycemic Drugs: Concurrent use with chlorpropamide may increase the risk of severe hyponatremia.

Nonsteroidal Anti-inflammatory Drugs: A possible interaction resulting in acute renal failure has been reported in a few patients on Dyazide (hydrochlorothiazide and triamterene) when treated with indomethacin, a nonsteroidal anti-inflammatory agent. Caution is advised in administering nonsteroidal anti-inflammatory agents with Dyazide (hydrochlorothiazide and triamterene) .

Lithium: Lithium generally should not be given with diuretics because they reduce its renal clearance and increase the risk of lithium toxicity. Read circulars for lithium preparations before use of such concomitant therapy with Dyazide (hydrochlorothiazide and triamterene) .

Surgical Considerations: Thiazides have been shown to decrease arterial responsiveness to norepinephrine (an effect attributed to loss of sodium). This diminution is not sufficient to preclude effectiveness of the pressor agent for therapeutic use.

Thiazides have also been shown to increase the paralyzing effect of nondepolarizing muscle relaxants such as tubocurarine (an effect attributed to potassium loss); consequently caution should be observed in patients undergoing surgery.

Other Considerations: Concurrent use of hydrochlorothiazide with amphotericin B or corticosteroids or corticotropin (ACTH) may intensify electrolyte imbalance, particularly hypokalemia, although the presence of triamterene minimizes the hypokalemic effect.

Thiazides may add to or potentiate the action of other antihypertensive drugs. See product labeling for concomitant use with other antihypertensive drugs.

The effect of oral anticoagulants may be decreased when used concurrently with hydrochlorothiazide; dosage adjustments may be necessary.

Dyazide (hydrochlorothiazide and triamterene) may raise the level of blood uric acid; dosage adjustments of antigout medication may be necessary to control hyperuricemia and gout.

The following agents given together with triamterene may promote serum potassium accumulation and possibly result in hyperkalemia because of the potassium-sparing nature of triamterene, especially in patients with renal insufficiency:

• blood from blood bank (may contain up to 30 mEq of potassium per liter of plasma or up to 65 mEq per liter of whole blood when stored for more than 10 days);
• low-salt milk (may contain up to 60 mEq of potassium per liter);
• potassium-containing medications (such as parenteral penicillin G potassium);
• salt substitutes (most contain substantial amounts of potassium).

Exchange resins, such as sodium polystyrene sulfonate, whether administered orally or rectally, reduce serum potassium levels by sodium replacement of the potassium; fluid retention may occur in some patients because of the increased sodium intake.

Chronic or overuse of laxatives may reduce serum potassium levels by promoting excessive potassium loss from the intestinal tract; laxatives may interfere with the potassium-retaining effects of triamterene.

The effectiveness of methenamine may be decreased when used concurrently with hydrochlorothiazide because of alkalinization of the urine.

Drug/Laboratory Test Interactions

Triamterene and quinidine have similar fluorescence spectra; thus, Dyazide (hydrochlorothiazide and triamterene) will interfere with the fluorescent measurement of quinidine.