Poppies produce a wide variety of useful medicines including opium, heroin, morphine, codeine. Each of these medicinal derivatives come from the unripe seed capsule or pod of P. somniferum. The ripe seed pods of the opium poppy are also the source of the commonly used culinary poppy seeds.

Morphine, thought to be the most effective painkiller known to medicine, acts largely on the sensory nerve cells of the cerebrum, blocking messages of pain from other parts of the body. In many (but not all) people it also causes euphoria and reduces anxiety, muscle tension, fears, and inhibitions. For those who like opioids, the pain reducing effect is less important than the effects on mood and suppression of physical sensations. The opiates in poppies decrease respiration (breathing) and can be dangerous at high doses. The constituent chemicals and even the raw poppy tea is considered highly addictive.

Codeine, an ingredient in many cough syrups is another alkaloid isolated from p. somniferum. It has both cough suppressent and analgesic properties and is often recommended to relieve minor pain.

Papaverine, a muscle relaxant that blocks the nerve impulses responsible for muscular contractions, is used to treat intestinal stomach spasms as well as the respiratory spasms triggered by asthma attacks.