ACE-031 (ramatercept, ActRIIB-Fc)
ACE031
A large engineered protein: a decoy activin receptor fused to part of an antibody, which soaks up myostatin and related signals. Never approved; development stopped after a trial in boys was halted over safety.
Legal status: Never approved; sold as a 'research chemical'. Banned in sport at all times (WADA S4.3, decoy activin receptors).
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
Sold as a 'research chemical' for muscle growth through myostatin and activin blockade. It was developed for Duchenne muscular dystrophy, but that trial was stopped early over safety concerns.
What people seek and what studies show
People hope for fast muscle gain. In 48 healthy postmenopausal women, the highest single dose raised lean mass by 3.3% and thigh muscle volume by 5.1% at day 29. In boys with Duchenne dystrophy there were trends toward more lean mass and bone density and less fat, not statistically significant, before the trial was stopped. Black-market products tested so far were not ACE-031.
Effects
Evidence: Limited human data — some human studies, small or short
Sought effects by goal (as reported)
Possible side effects
Possible does not mean certain: whether they appear depends on dose, duration, individual response and monitoring. Below — what to watch for and how to notice it early.
4 possible side effects
level · how often it is reportedWhat the levels mean
Level: general category from the literature, not your personal risk
How often
- common
- reported often
- possible
- reported in some people
- rare
- reported occasionally
How to lower the risks
General ways to lower the chance of each side effect. No measure removes a risk completely.
Products obtained without a prescription are often fake, mislabeled or non-sterile, and there is no way to check at home. For legal supplements, look for third-party testing (Informed Sport, NSF).
Do not combine several blood-thinning products (aspirin, painkillers such as ibuprofen, high intakes of fish oil, nattokinase, vitamin E) without a doctor; tell doctors and dentists before procedures; alcohol adds to the risk of stomach bleeding.
What is unknown cannot be lowered, only avoided; tell your doctor what you have taken.
Low-level side effects
Check-ups and blood tests
Which tests and check-ups to do and when. This is a guide — agree the exact schedule with your doctor.
Which doctors can help
Get medical help at once if
- Black or bloody stools, vomiting blood or “coffee grounds”, a sudden severe headache, or bleeding that will not stop — seek urgent care.
In an emergency, call your local emergency number.
For women
The only healthy-volunteer study was in postmenopausal women. It also blocks activin, which helps regulate FSH; effects on periods, fertility and pregnancy are unknown.
Myth & fact
“ACE-031 is a proven muscle builder from clinical trials.”
One dose added a few percent of lean mass in a small study, but development stopped after nosebleeds and dilated vessels in boys, and black-market vials were a different protein.
Combinations
No specific combination notes for this substance yet. The stack check still adds up side effects that several substances share.
Sources
Possible side effects by body system, combinations, how to lower the risks and which tests to do — free.
Open the stack check