Insulin (rapid- and short-acting)
Humalog, NovoRapid, Novolog, Apidra, Fiasp, Humulin R, Actrapid, Insulin lispro
Forms: Rapid-acting analogs (lispro, aspart, glulisine) and short-acting regular human insulin; long-acting insulins are a different group.
The hormone that drives glucose and amino acids into cells. Used without diabetes to 'push' nutrients into muscle — among the most acutely dangerous drugs in bodybuilding.
Legal status: Prescription medicine for diabetes. Banned in sport at all times (WADA S4.4.2).
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
Medically: diabetes. In bodybuilding: for glycogen 'fullness' and anabolic signaling, often with GH or steroids; gains are partly glycogen, water and fat. There is no safe way to use it without diabetes.
What people seek and what studies show
People hope for fuller muscles, faster refueling after training and extra size. In human infusion studies insulin mainly slowed muscle protein breakdown; no controlled study shows added muscle in healthy athletes, while severe hypoglycemia has put bodybuilders into comas.
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.
4 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
- Shaking, cold sweat, sudden hunger, confusion — fast sugar at once; very drowsy, unable to swallow or unconscious — nothing by mouth, call emergency services, glucagon if prescribed. Night sweats or nightmares can mean lows in sleep.
- Racing or irregular heartbeat that does not settle at rest, dizziness, fainting, chest pain — call emergency services.
In an emergency, call your local emergency number.
Myth & fact
“If you eat enough carbs, insulin is safe and builds only muscle.”
Insulin stores fat as readily as glycogen, and no eating plan makes it safe: a severe low can kill within hours.
Combinations
Insulin 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.
FurosemideHydrochlorothiazideClenbuterolSalbutamolLiothyronineLevothyroxineEach of these lowers blood sugar in its own way, so with insulin the lows come deeper, last longer and are harder to predict. Confusion, sweating or drowsiness is an emergency; a severe low can kill.
IGF-1 LR3MetforminSemaglutideTirzepatideRetatrutide (investigational triple agonist)BerberineAlpha-lipoic acidLiraglutideCagrilintide (investigational amylin analogue)Mecasermin (recombinant IGF-1, Increlex)DES(1-3) IGF-1A racing pulse and tremor are the body's early alarm for low blood sugar. Nebivolol blunts them, so a dangerous low can go unnoticed until it shows as confusion or fainting.
NebivololIGF-1 LR3Mecasermin (recombinant IGF-1, Increlex)DES(1-3) IGF-1Glucocorticoids raise blood sugar, after a depot injection often for days, and work against insulin, IGF-1 and GLP-1 drugs. Sugar can run high while the glucocorticoid acts and then fall as its effect wears off while the sugar-lowering drug keeps working. Only glucose checks show these swings.
IGF-1 LR3Mecasermin (recombinant IGF-1, Increlex)DES(1-3) IGF-1SemaglutideTirzepatideRetatrutide (investigational triple agonist)LiraglutideA racing pulse is one of the body's early alarms for low blood sugar. Bisoprolol and carvedilol blunt it, so a dangerous low can go unnoticed until it shows as confusion or fainting. Carvedilol, which also blocks beta-2 receptors, can in addition make a low deeper and slower to recover from.
IGF-1 LR3Mecasermin (recombinant IGF-1, Increlex)DES(1-3) IGF-1