Anxiolytic

L-theanine is an amino acid found almost only in tea. Taken at 200 to 400 mg a day, it may reduce stress and anxiety in people under stressful conditions. Its best-known use is alongside caffeine, where the pair improves attention switching more than either alone. A 2025 meta-analysis found small improvements in subjective sleep.

Selank is a synthetic heptapeptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) described as an analogue of tuftsin. It is studied as an anxiolytic. In Russian clinical studies of generalised anxiety and related disorders, it matched the benzodiazepine medazepam on anxiety, and adding it to phenazepam reduced phenazepam's side effects. Proposed mechanisms include slowing enkephalin breakdown and modulating GABA-A receptors.