Comparison guide

Ashwagandha or rhodiola for stress?

These are sold almost interchangeably for stress, but the evidence is not level. Ashwagandha has small positive trials on perceived stress and cortisol, L-theanine has a small effect on acute stress, and rhodiola's fatigue and mood trials are weak or negative.

The options, compared

Option	Evidence	Best for	The honest note
Ashwagandha	Moderate evidence	Ongoing stress, short term	Small, often industry-funded trials showed lower perceived stress and cortisol with root extract such as 300 mg twice daily of KSM-66. Studied for up to about 3 months; rare liver toxicity has been reported, and avoid it in pregnancy or thyroid disease without supervision.	View
Rhodiola Rosea	Limited evidence	Skip for now	Its fatigue trials are small and at high or unclear risk of bias, and in the one rigorous depression trial it did no better than placebo. It can be stimulating and may interact with drugs metabolised by CYP3A4.	View
L-Theanine	Moderate evidence	Predictable stressful moments	A meta-analysis of 31 trials found small improvements in acute stress and state anxiety at 200–400 mg taken 30–60 minutes beforehand; effects on chronic anxiety were much less convincing. One of the better-tolerated supplements.	View

Our verdict

For ongoing stress, ashwagandha has the better, though still small, evidence; for a stressful moment you can see coming, L-theanine is the gentler option with a small effect. Rhodiola is not worth choosing for stress on current evidence. Skip ashwagandha if you are pregnant or have thyroid disease, unless under medical supervision.