California poppy leaves were used medicinally by Native Americans, and the pollen was used cosmetically. The seeds are used in cooking.
An aqueous extract of the plant has sedative and anxiolytic action. The extract acts as a mild sedative when smoked. The effect is far milder than that of opium. California poppy contains a different class of alkaloids:
"An aqueous alcohol extract of Eschscholzia californica has been evaluated for benzodiazepine, neuroleptic, antidepressant, antihistaminic and analgesic properties. The plant extract did not protect mice against the convulsant effects of pentylenetetrazol, and did not cause muscle relaxant effects, but appeared to possess an affinity for the benzodiazepine receptor. The extract induced peripheral analgesic effects in mice but did not possess antidepressant, neuroleptic or antihistaminic effects."