Hydrochlorothiazide
HCTZ, Hydrodiuril, Hypothiazid, Chlorthalidone, Indapamide
Forms: Related thiazides: chlorthalidone, indapamide, bendroflumethiazide; often combined in one pill with BP drugs or potassium-sparing agents (triamterene, amiloride). With those combinations potassium can also rise, dangerously so with potassium supplements or ARBs.
A thiazide diuretic and first-line blood-pressure medicine. Milder and slower than furosemide but long-acting, with marked losses of potassium, sodium and magnesium.
Legal status: Prescription medicine; prohibited at all times under WADA S5 (diuretics).
What it gives
What people use it for and what the sources report. Strength is a general category from the literature: mild, clear or strong.
Purpose
Used before contests to reduce water under the skin, often in combination pills. There is no safe way to use it for appearance: it keeps draining potassium and sodium for many hours, and stacking diuretics multiplies the danger. Medical: hypertension and edema.
What people seek and what studies show
A milder diuretic than furosemide: it removes less water at a time but acts longer, with steady losses of sodium, potassium and magnesium. In medicine it lowers blood pressure, partly through that fluid loss. The idea that it removes water 'under the skin' is untested — diuretics draw water from the blood and the whole body, and no study links them to a better stage look.
Effects
Evidence: Approved medicine — studied in people for its medical use
Possible side effects
With an extreme-risk substance some of these can be life-threatening or permanent; no dose, test or early sign makes it safe. Below — what each risk looks like; the signs that need urgent help are in block 04.
5 possible side effects
level · how often it is reportedHow to lower the risks
Extreme risk. No measure makes using this substance for sport safe: severe, including life-threatening, consequences are possible. The only reliable way to avoid these risks is not to use it.
If a doctor prescribed this medicine to treat you, do not stop taking it on your own — discuss it with your doctor.
Warning signs that need urgent help are listed in block 04.
Check-ups and blood tests
For an extreme-risk substance there is no testing schedule.
Get medical help at once if
- Racing or irregular heartbeat that does not settle at rest, dizziness, fainting, chest pain — call emergency services.
- Severe cramps, marked weakness, palpitations, dizziness on standing, very little urine — seek urgent care.
- Much less urine than usual, cola-colored urine, new swelling, flank pain — see a doctor now.
- A mole that grows, bleeds, itches or changes color or shape — see a dermatologist promptly.
In an emergency, call your local emergency number.
Myth & fact
“A 'mild' diuretic is safe before a show.”
Thiazides act for many hours and keep draining potassium and sodium; combined with fluid restriction or other diuretics, they have caused paralysis and dangerous QT prolongation, and carb loading can push potassium lower still.
Combinations
The diuretic flushes potassium out while clenbuterol drives it into cells. In studies a diuretic plus a beta-2 agonist lowered potassium and changed the ECG more than either alone; very low potassium can cause paralysis and fatal arrhythmia.
ClenbuterolFurosemideThe diuretic flushes potassium out while salbutamol drives it into cells. In studies the pair lowered potassium and changed the ECG more than either alone; very low potassium can cause paralysis and fatal arrhythmia.
SalbutamolFurosemideInsulin moves potassium into cells. Loop and thiazide diuretics, clenbuterol, salbutamol and thyroid hormone lower blood potassium too, so together it can drop suddenly: muscle weakness, paralysis or a life-threatening arrhythmia.
Insulin (rapid- and short-acting)FurosemideClenbuterolSalbutamolLiothyronineLevothyroxineWhen the body is short of water, telmisartan blocks the hormone that keeps the kidneys filtering. With a diuretic, especially during water cutting, heavy sweating or NSAID use, blood pressure can drop and acute kidney injury can follow.
TelmisartanFurosemideSpironolactoneDehydration from diuretics or water cutting can reduce kidney function, so metformin builds up and the rare but life-threatening lactic acidosis becomes more likely. Unusual tiredness, muscle pain, fast breathing or belly pain need urgent care.
MetforminFurosemideVomiting and diarrhea, common early on GLP-1 drugs, drain fluid; a diuretic on top can tip the kidneys into acute injury. Their labels warn of kidney injury after fluid loss.
FurosemideSpironolactoneThiazides make the kidneys hold on to calcium while vitamin D increases its absorption, so blood calcium can climb: thirst, nausea, constipation, confusion and strain on the kidneys. Calcium and 25(OH)D tests show it.
Vitamin D3 (± K2)Steroids raise red-cell mass, and dehydration from diuretics concentrates the blood further; thicker blood raises the chance of clots and strain on the heart, on top of the diuretic's own arrhythmia risk.
FurosemideTadalafil lowers blood pressure a little, and so do these drugs; the effects add up. With dehydration, heat or alcohol this can mean dizziness or fainting, especially when standing up quickly.
TadalafilFurosemideSpironolactoneTelmisartanNebivololLosartan / valsartan (angiotensin receptor blockers)ACE inhibitors (ramipril, perindopril, lisinopril)AmlodipineBisoprololCarvedilolGlucocorticoids make the kidneys lose potassium. Loop and thiazide diuretics flush it out too, and clenbuterol and salbutamol push it into cells, so potassium can fall low: cramps, weakness, palpitations, and in severe cases a dangerous heart rhythm. The labels ask for potassium to be watched with such combinations.
FurosemideClenbuterolSalbutamolWhen the body is short of water, ACE inhibitors and sartans block the hormone that keeps the kidneys filtering. With a diuretic, especially during water cutting, heavy sweating or NSAID use, blood pressure can drop and acute kidney injury can follow.
FurosemideThiazides make the kidneys hold on to calcium, so calcium from supplements is excreted less and blood calcium can climb: thirst, nausea, constipation, confusion and strain on the kidneys. A calcium test shows it.
CalciumToremifene prolongs the QT interval of the heartbeat, and its label rules out use with uncorrected low potassium. Loop and thiazide diuretics, clenbuterol and salbutamol lower potassium, which makes a dangerous rhythm disturbance more likely. Fainting, a seizure or a fast, irregular heartbeat needs emergency care.
ToremifeneFurosemideClenbuterolSalbutamol