Can You Take Caffeine and Suntheanine (L-Theanine) Together?

Dose or timing may matter

The short answer

Suntheanine (L-Theanine) promotes relaxation and alpha brain wave activity, while caffeine is a CNS stimulant. While often intentionally paired, their opposing mechanisms partially cancel each other's primary effects.

How to arrange timing

The caffeine-theanine combination is well-studied and generally well-tolerated. A 2:1 theanine-to-caffeine ratio is commonly recommended.

Reference

Reference noted for this combination: Owen GN, et al. The combined effects of L-theanine and caffeine on cognitive performance and mood. Nutr Neurosci. 2008;11(4):193-198.

Important context

Whether supplements suit you together also depends on dose, product formulation, health conditions, and medication use. Ask a doctor or pharmacist first if you take medication, are pregnant or breastfeeding, or have a chronic condition.