Hydrene 25_50

Hydrene 25_50 - Precautions | Dosage | Effects

This article was medically reviewed by M.Pharm, Marko Tanaskovic on Sun, 12 Jan 2020. To read more about an author, click here.

Hydrene 25/50 is a drug that contains two active substances: hydrochlorothiazide (25 mg) and triamterene (50 mg). Both substances belong to group of diuretics, with triamterene being potassium-sparing diuretic (antikaliuretic agent - reduces excretion of potassium).

Hydrene 25/50 is a diuretic medicine that contains combination of natriuretic and antikaliuretic agents, meaning that increases excretion of sodium, which consequently leads to an excessive excretion of water, thus reducing the pressure on blood vessels. Hydrochlorothiazide increases excretion of potassium, which may lead to hypokalemia. Hypokalemia can be severe and it can lead to serious irregular heartbeats. However, triamterene works by increasing excretion of sodium, while sparing potassium by reducing its excretion.

This is why, combining these two diuretics makes perfect sense - it achieves appropriate hypotensive effect, and does not increase risk of electrolyte imbalance, so it has less potential for side effects.

Once you swallow the Hydrene 25/50 tablet, you may expect diuretic effect to occur promptly, within 1 hour, with maximum effect occurring after three hours of administration. Diuretic effect usually lasts 7-9 hours after taking the tablet.

Hydrene 25/50 is indicated for the treatment of hypertension (high blood pressure). It can be used alone or in combination with other antihypertensive drugs. It is most commonly used in the treatment of patients who have hypertension and need to take thiazide diuretics, but must not experience hypokalemia.

Hydrene 25/50 is also indicated for the treatment of edema, caused by various factors (heart disease, liver disease, kidney disease, or taking some medications).

How to Take Hydrene 25/50 Tablets?

Usual initial dose in the treatment of hypertension is one tablet of Hydrene (containing 25 mg of hydrochlorothiazide and 50 mg of triamterene) a day, while the initial dose in the treatment of edema is one tablet of Hydrene 25/50 two times a day.

Your doctor may change the dose based on the severity of the condition you have. Your doctor will decide what dose works best for you.

Swallow the tablet whole, with a full glass of water. If needed, Hydrene 25/50 mg tablets can be broken in half, if that was recommended by your doctor or pharmacist.

It is best to take Hydrene 25/50 in the morning, following the breakfast, as this way you will avoid frequent urination at night. If you are taking Hydrene 25/50 two times a day, then you should take your first dose at 8 AM and second dose at 5 or 6 PM.

It is best to take Hydrene tablets after the meal, to reduce the risk of gastrointestinal side effects.


Hydrene 25/50 should not be used in patients who are allergic to hydrochlorothiazide or triamterene. If you are allergic to antibiotics called sulfonamides (such as sulfadiazine, sulfamethaxozole (commonly known as Bactrim), sulfafurazole, sulfanitran, etc.), you need to inform your doctor prior starting Hydrene 25/50, as patients who are allergic to sulfonamides may develop cross-allergic reaction to hydrochlorothiazide as well. If you notice any symptoms of an allergy (swelling of tongue, difficulty in swallowing, difficulty in breathing, etc.), you must inform your doctor at once.

Hydrene 25/50 should also be avoided in patients who have kidney damage, as Hydrene 25/50 mg mainly works through renal tubules. If you are experiencing anuria (production of urine less than 50 ml/day) or oliguria (production of urine less than 400 ml/day), you need to inform your doctor. Anuria and oliguria might be the signs of severe kidney damage and these patients should not use Hydrene 25/50 tablets.

Hydrene 25/50 should also be avoided in patients who have high levels of potassium in the blood (hyperkalemia) or are taking potassium supplements or other drugs that might increase level of potassium (e.g. spironolactone).

Before starting Hydrene 25/50, you also need to inform your doctor if you have any of following conditions:

  • Diabetes.
  • High cholesterol.
  • Gout
  • Liver problems.
  • Heart problems.
  • Systemic lupus erythematosus.

Hydrene 25/50 might cause worsening of symptoms/status of abovementioned disorders, and should be avoided in these patients.

Use of Hydrene 25/50 in Pregnancy

Hydrene 25/50 belongs to Pregnancy Category C (classified by FDA) and it should not be used in pregnancy unless clearly needed. Your doctor will evaluate the risk/benefits of taking this medicine during pregnancy.

Triamterene is excreted into breast milk, therefore, breastfeeding should be discontinued while on Hydrene 25/50 therapy.


Hydrene 25/50 might interact with following drugs:

  • Potassium supplements or other drugs that might increase potassium levels in the blood (e.g. spironolactone - a potassium-sparing diuretic).
  • Inhibitors of angiotensin-converting enzyme, such as: ramipril, enalapril, lisinopril, perindopril, etc. These drugs are used to treat hypertension.
  • Monoamine oxidase inhibitors, such as: izocarboxazid, tranylcipromine, phenelzine, selegiline, linezolid, etc.
  • Group of drugs called phenothiazines, such as: trifluoroperazine, fluphenazine, chlorpromazine, mesoridazine, etc. These drugs are used to treat schizophrenia and other psychiatric disorders.
  • Non-steroidal anti-inflammatory drugs (NSAIDs), such as: ibuprofen, flurbiprofen, indomethacin, etc.
  • Opioid analgesics, such as: morphine, tramadol, codeine, etc.
  • Muscle relaxants, such as tizanidine.
  • Medicines used to treat arrhythmias, such as: dronedarone, amiodarone, dofetilide, etc.
  • Dolasetron - medicine used to prevent nausea and vomiting following chemotherapy.
  • Lithium - an antipsychotic drug.

Inform your doctor about all medicines (including OTC products) you are taking, before you start taking Hydrene 25/50.

Side Effects

Hydrene 25/50 is associated with following side effects:

  • Muscle cramps.
  • Impotence.
  • Blood dyscrasia (anemia, agranulocytosis and thrombocytopenia).
  • Acute renal failure.
  • Electrolyte imbalance (hypo- or hyperkalemia, hyperglycemia, hypercalcemia and hyponatremia).
  • Pancreatitis.
  • Gastrointestinal side effects (nausea, vomiting, constipation, diarrhea, abdominal pain, etc.).
  • Hypotension.
  • Irregular heartbeats.
  • Photosensitivity.
  • Fatigue.
  • Vertigo.
  • Stevens-Johnson syndrome.

Tell your doctor immediately if you notice any side effect.


  1. TGA
  2. FDA

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