Absorption of THC by the gastrointestinal tract is quite effective, but relatively slow and erratic.359 The food content of the stomach may affect the rate of absorption. Even though cannabis resin is poorly soluble in water, effective emulsions or suspensions of cannabinoids in water can be achieved for oral consumption, and in the East cannabis is often used in making tea or other beverages. Mild bhang drinks, served cold, are common in parts of India. In some countries, hashish is incorporated into buttered candies, called majoon, or into other foods. The effects of cannabis taken orally usually begin after about an hour and gradually reach a peak within several hours, then slowly decline.
Cannabis is also effective when administered rectally.
The subjective effects of eating cannabis are sometimes said to be noticeably different, qualitatively, from those of smoking. It is uncertain whether this alleged difference might be due to chemical changes resulting from the heat in smoked material, the effects of the digestive juices or other metabolic processes after ingestion, or differences in rapidity and efficiency of absorption and distribution with the two methods. Since Delta 9 THC is poorly soluble in water, adequate injection procedures are difficult to achieve. A variety of solvents and other agents have been employed as injection vehicles in animal experiments with varying degrees of success. Water soluble THC derivatives have recently been developed, but their similarity to natural THC has not yet been established.