Spironolactone and Hydrochlorothiazide

Spironolactone and hydrochlorothiazide tablets are approved for several conditions involving fluid overload and high blood pressure. Supported uses include:

• Congestive heart failure: managing edema and sodium retention when other treatments haven't worked well enough, or correcting low potassium caused by other diuretics, including in patients also taking digitalis
• Liver cirrhosis with edema or ascites (abdominal fluid): used as maintenance therapy alongside rest and fluid/sodium restriction, since aldosterone levels can be very high in this condition
• Nephrotic syndrome: for patients who haven't responded adequately to treating the underlying disease, fluid/sodium restriction, or other diuretics
• Essential hypertension (high blood pressure): to lower blood pressure when other measures are inadequate, and to correct diuretic-induced low potassium in patients with high blood pressure
• Pregnancy-related edema: only when edema is due to a medical (pathologic) cause — routine use for normal pregnancy swelling is not recommended

Spironolactone blocks aldosterone — a hormone that signals the kidneys to retain sodium and water and excrete potassium. By blocking aldosterone receptors in the kidney's collecting tubules, spironolactone helps the body shed excess fluid while holding onto potassium. Hydrochlorothiazide works in a separate part of the kidney (the cortical diluting segment) to block sodium and water reabsorption, adding a second, complementary diuretic effect. Together, the two drugs reduce blood volume, body weight, and blood pressure more effectively than either alone — and spironolactone's potassium-sparing action helps counterbalance the potassium loss that hydrochlorothiazide tends to cause.

Spironolactone and hydrochlorothiazide tablets are taken by mouth, either as a single daily dose or split into smaller doses throughout the day. Your prescriber will adjust the dose based on how you respond — the right amount varies from person to person. Food can nearly double the absorption of spironolactone, so it's worth asking your doctor or pharmacist whether to take it consistently with or without a meal.

• Do not take extra potassium supplements or potassium-rich salt substitutes unless your doctor specifically recommends it
• The diuretic (fluid-removing) effect starts quickly and can last two to three days after you stop taking the medication
• If you miss a dose, follow your prescriber's or pharmacist's guidance — do not double up

Like all medications, this combination can cause side effects. Common ones include:

• Dizziness or lightheadedness, especially when standing up quickly (orthostatic hypotension)
• Nausea, vomiting, stomach cramps, or diarrhea
• Headache, drowsiness, or mental confusion
• Muscle cramps or weakness
• Breast tenderness or enlargement (gynecomastia) in men or women
• Irregular menstrual periods or missed periods
• Increased sensitivity to sunlight (photosensitivity)

Seek medical help right away for serious reactions: severe skin blistering or peeling (Stevens-Johnson Syndrome or toxic epidermal necrolysis), sudden eye pain or vision loss, signs of very high potassium (muscle weakness, irregular heartbeat), yellowing of the skin or eyes, or signs of a severe allergic reaction (trouble breathing, facial swelling).

• High potassium (hyperkalemia): The biggest risk with this combination. Avoid potassium supplements, potassium-containing salt substitutes, ACE inhibitors, angiotensin receptor blockers, NSAIDs, and other potassium-sparing diuretics unless your doctor closely monitors you. Symptoms include muscle weakness, irregular heartbeat, and tingling.
• Acute angle-closure glaucoma: Hydrochlorothiazide can rarely trigger sudden-onset eye pain, blurred vision, or a sharp drop in vision — usually within hours to weeks of starting. Stop the medication and get medical attention immediately. People with a history of sulfonamide or penicillin allergy may be at higher risk.
• Liver disease: Even small changes in fluid and electrolyte balance can trigger hepatic coma (a serious loss of brain function) in people with liver problems. Use with caution.
• Kidney disease: Thiazide diuretics may worsen kidney function in people with significant kidney impairment. People with no urine output (anuria) or acute kidney failure should not take this medication.
• Skin cancer risk: Long-term hydrochlorothiazide use has been associated with a small increased risk of squamous cell skin cancer, particularly in white patients taking high cumulative doses. Use sun protection and get regular skin checks.
• Tumor risk in rats: Spironolactone has caused tumors in rat studies. The label states this medication should only be used for the conditions described, and unnecessary use should be avoided.

This combination interacts with several medications and substances — always tell your doctor and pharmacist everything you take:

• ACE inhibitors, angiotensin receptor blockers, other potassium-sparing diuretics, aldosterone blockers: Raise the risk of dangerously high potassium
• NSAIDs (e.g., ibuprofen, indomethacin): Can raise potassium to dangerous levels and weaken the diuretic and blood-pressure-lowering effects
• Lithium: Diuretics slow the kidneys' removal of lithium, sharply raising the risk of lithium toxicity — generally should not be combined
• Digoxin: Spironolactone can increase digoxin blood levels, raising the risk of digoxin toxicity and potentially fatal heart rhythm problems
• Potassium supplements or salt substitutes with potassium: Can push potassium levels dangerously high
• Alcohol, barbiturates, or opioid pain relievers: Can worsen low blood pressure and dizziness when standing
• Diabetes medications (pills or insulin): Thiazides can affect blood sugar; dose adjustments of your diabetes medication may be needed
• Aspirin: May reduce the effectiveness of spironolactone
• Mitotane (a cancer drug): Spironolactone lowers mitotane levels in the blood — concurrent use should be avoided
• Cholestyramine: Has been linked to a serious acid-base imbalance (hyperkalemic metabolic acidosis) when used with spironolactone

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

• You have kidney disease, no urine output, or acute kidney failure — this medication is contraindicated in those situations
• You have Addison's disease (adrenal gland insufficiency) — contraindicated
• You have high potassium (hyperkalemia) or high calcium (hypercalcemia) levels — contraindicated
• You have severe or acute liver failure — may also be contraindicated
• You are allergic to sulfonamide drugs or thiazide diuretics — the hydrochlorothiazide component is a thiazide and sulfonamide derivative
• You are pregnant or trying to become pregnant — routine use is not recommended; discuss with your doctor if edema has a medical cause
• You take other diuretics, blood pressure medications, heart medications, or over-the-counter pain relievers — many interact with this combination
• You have or have had systemic lupus erythematosus — thiazides may worsen it

Taking too much of this combination can cause drowsiness, mental confusion, nausea, vomiting, dizziness, or a skin rash. Electrolyte imbalances — either high potassium or low potassium and sodium — are the main dangers, and people with kidney problems are at highest risk of severe potassium buildup. If overdose is suspected, seek emergency medical help; treatment focuses on supporting hydration, electrolyte balance, and vital functions — there is no specific antidote.

Both spironolactone and hydrochlorothiazide reduce the amount of exchangeable sodium, blood plasma volume, body weight, and blood pressure. Spironolactone blocks aldosterone receptors in the kidney, while hydrochlorothiazide prevents sodium and water reabsorption in a different kidney segment — giving additive effects when used together. The combination lowers both systolic (top number) and diastolic (bottom number) blood pressure in many patients with essential hypertension, even when aldosterone levels are within the normal range.

Spironolactone is rapidly and extensively broken down by the body into active metabolites that carry out most of its therapeutic effects; these metabolites have half-lives ranging from roughly 14 to 17 hours. Taking spironolactone with food can nearly double the amount absorbed, so consistency matters. Hydrochlorothiazide, by contrast, is absorbed quickly after an oral dose — its effects begin within about one hour, peak at one to two hours, and last six to twelve hours. Hydrochlorothiazide is excreted largely unchanged in the urine, with a half-life of four to five hours.

Store below 77°F (25°C).