N,N-Dimethylglycine HCl is the hydrochloride salt of DMG, a methyl donor made from the amino acid glycine. The salt form dissolves in water more easily and stays stable longer than the free base, which is why supplement makers use it.
Athletes and active people take it to boost energy and curb exercise fatigue. Mental focus is another reason some people reach for it, though the proof behind these uses is thin.
People typically take DMG HCl by mouth before a workout. Mix the powder with water or juice to soften the sour taste. Taking it with food can help avoid mild stomach trouble.
Side effects can include nausea or digestive upset. If you are pregnant or nursing, talk to a healthcare professional before you take it.