May interfere with the action of thyroid hormones and should not be used during treatment with thyroid hormones.
– Brinker F. — Herb Contraindications and Drug Interactions. — Eclectic Institute, 1997, 21, 29-30.

Taken at the same time as standard sedative drugs, excessive sedation may occur.

Avoid this herb if you have eye problems or glaucoma.
– Leach EH, Lloyd JPF. — Experimental ocular hypertension in animals. — Trans Ophthalm Soc UK 1956;76:453-60.