Safety Profile
Overall safety rating: Generally Safe
Glycine Side Effects & Safety
This content is for informational purposes only and does not constitute medical advice. Consult your healthcare provider before starting any supplement. Full disclaimer
Potential Side Effects
- Extremely well tolerated — one of the safest amino acid supplements
- Mild gastrointestinal discomfort at very high doses (rare at 3g)
- Nausea at very high doses (rare)
- Soft stools at very high doses (uncommon)
- No sedation, grogginess, or hangover effects
Drug & Supplement Interactions
- Clozapine — glycine may affect clozapine efficacy (conflicting evidence)
- Antipsychotic medications — glycine modulates NMDA receptors, potentially interacting with antipsychotic mechanisms
- No significant interactions at typical sleep doses for most people
Maximum Dose
Do not exceed: 5g/day for sleep purposes (glycine is used at much higher doses therapeutically for other conditions)
References
- Bannai M, Kawai N, Ono K, Nakahara K, Murakami N (2012). The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Frontiers in Neurology. DOI PubMed
- Inagawa K, Hiraoka T, Kohda T, Yamadera W, Takahashi M (2006). Subjective effects of glycine ingestion before bedtime on sleep quality. Sleep and Biological Rhythms. DOI
- Kawai N, Sakai N, Okuro M, et al. (2015). The sleep-promoting and hypothermic effects of glycine are mediated by NMDA receptors in the suprachiasmatic nucleus. Neuropsychopharmacology. DOI PubMed
- Yamadera W, Inagawa K, Chiba S, Bannai M, Takahashi M, Nakayama K (2007). Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes. Sleep and Biological Rhythms. DOI