Glycine
The simplest amino acid and an inhibitory neurotransmitter; also a building block of collagen. Very well tolerated.
Legal status: Sold freely as a supplement (registered as an OTC medicine in Russia); not prohibited in sport.
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 for deeper sleep and better next-day alertness. Small Japanese trials show better subjective sleep, probably via a slight drop in core body temperature; evidence quality is low.
What people seek and what studies show
After three nights of shortened sleep, volunteers given glycine reported less daytime fatigue and did better on a reaction-time test. In rats it acts on the brain's body clock and widens skin blood vessels, so the body sheds heat before sleep. A 2024 systematic review found sleep benefits in healthy people, but only from small studies at high risk of bias.
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.
1 possible side effect
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
For 1 of 1 possible side effect there are specific ways to lower the chance: everyday measures, supplements and options a doctor may consider. No measure removes a risk completely.
Low-level side effects
How each option helps (2)
- Working with a doctor — Assesses persistent vomiting or severe belly pain (possible pancreatitis or gallstones) and adjusts prescribed GLP-1 treatment when nausea persists.
- Pancreatin + dimeticone (Pankreoflat) — May ease heaviness and gas after meals; can cause nausea or diarrhea. Not for pork or cow's milk protein allergy (anaphylaxis reported) or early acute pancreatitis.
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.
Myth & fact
“Glycine works like a sleeping pill.”
No. It is not a sedative; small studies show a modest gain in subjective sleep quality, likely via a slight drop in core body temperature.
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