Furosemide
Lasix, Frusemide, Torasemide, Torsemide, Bumetanide
Forms: Other loop diuretics — torasemide, bumetanide — carry the same risks.
A powerful, fast-acting loop diuretic: the kidneys flush out water together with sodium, potassium and magnesium. Prescribed for heart failure, edema and kidney disease.
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
Misused before contests or weigh-ins to strip water for a drier look. There is no safe way to do this: its speed and power cause severe dehydration and low potassium that can stop the heart, and bodybuilders have died on or just after show day.
What people seek and what studies show
It makes the kidneys flush out water and salts quickly, and the water comes first from the blood. In a controlled study in runners, losing about 2% of body weight this way cut plasma volume by about 10% and slowed 5 km and 10 km race times. No study shows a better stage look: a review of peak-week practices found no evidence that manipulating water and salt is effective or safe.
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.
3 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.
In an emergency, call your local emergency number.
Myth & fact
“Diuretics are what make you look hard and dry on stage.”
Pulling water out of the blood can leave muscles flat and cramping while blood pressure falls. Bodybuilders have collapsed and died on or just after show day after extreme dehydration.
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.
ClenbuterolHydrochlorothiazideThe 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.
SalbutamolHydrochlorothiazideInsulin 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)HydrochlorothiazideClenbuterolSalbutamolLiothyronineLevothyroxineWhen 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.
TelmisartanHydrochlorothiazideSpironolactoneDehydration 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.
MetforminHydrochlorothiazideVomiting 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.
HydrochlorothiazideSpironolactoneSteroids 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.
HydrochlorothiazideTadalafil 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.
TadalafilHydrochlorothiazideSpironolactoneTelmisartanNebivololLosartan / 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.
HydrochlorothiazideClenbuterolSalbutamolWhen 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.
HydrochlorothiazideToremifene 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.
ToremifeneHydrochlorothiazideClenbuterolSalbutamol