Botanical name: 

The dried or concrete milk-juice of Lactuca virosa, Linné (Nat. Ord. Compositae). South and Central Europe. Dose, 5 to 20 grains.
Common Name: Lettuce Opium.

Principal Constituents.—Lactucin (C11H14O4), lactucerin (lactucone), lactucopicrin, lactucic acid, and a comphoraceous volatile oil.
Preparations.—1. Tinctura Lactucarii, Tincture of Lactucarium, (50 per cent strength). Dose, 30 to 60 drops.
2. Syrupus Lactucarii, Syrup of Lactucarium (prepared from Tincture). Dose, 1-3 fluidrachms.

Action and Therapy.—A non-constipating calmative and feeble hypnotic, sometimes proving useful in insomnia from mental overwork and, as a syrup, in the cough of phthisis. Even garden lettuce (Lactuca sativa) relieves irritation of the broncho-pulmonic membranes and has a tendency to induce drowsiness. Lactucarium is often inert; when a good preparation can be obtained it is fairly sedative for irritable children.

The Eclectic Materia Medica, Pharmacology and Therapeutics, 1922, was written by Harvey Wickes Felter, M.D.