Chimps in an open-air forested enclosure have spotted veterinarian Raven Jackson carrying a caddy packed with their morning's juice treats and frozen bananas. A half-dozen dark-haired chimpanzees crowd the wire metal gate and wait for her to dispense the goodies.
Codeine is a narcotic. It is a pain reliever and a cough suppressant. Promethazine is an antihistamine. It blocks the effects of the naturally occurring chemical histamine in your body. The combination of codeine and promethazine is used to treat cold or allergy symptoms such as runny nose, sneezing, and cough.
Promethazine is an antihistamine and works by blocking a certain natural substance that your body makes during an allergic reaction. Its other effects (such as anti-nausea, calming, pain relief) may work by affecting other natural substances (such as acetylcholine) and by acting directly on certain parts of the brain.