Cannabis comes from the cannabis sativa plant. It is the most commonly used illicit drug in New Zealand.

The active chemical in cannabis is THC (Delta-9 etrahydrocannabinol). The more THC cannabis contains, the stronger it is. Cannabis is a depressant. It can have mild hallucinogenic effects. Street or slang names for marijuana include Pot, Grass, Dope, Electric Puha, and Hooch.

Cannabis has three main forms: marijuana, hashish and hash oil.

Marijuana is the most common and least powerful form of cannabis. It is the dried leaves and flowers of the plant. Marijuana looks like chopped grass, and is grey-green to greenish-brown. Its texture can be fine or coarse. It can contain seeds and twigs from the plant. The flowers or “heads” are the most potent part of the plant. Marijuana is smoked in hand-rolled cigarettes (joints) or in a pipe (bong).

Hashish (hash) is dried cannabis resin, which comes in small blocks. The blocks are light brown to nearly black. The concentration of THC in hashish is higher than in marijuana. That produces stronger effects. Hash is added to tobacco and smoked, or baked and eaten in foods such as “hash cookies”.

Hash oil is a thick, oily liquid, golden-brown to black, which can be extracted from hashish. It is usually spread on the tip or paper of cigarettes and then smoked. Hash oil is more powerful than the other forms of cannabis. A very small amount can have a strong effect, lasting two-three hours.

Cannabis can make users feel happy, relaxed and comfortable. They might feel less inhibited, friendlier and laugh spontaneously. It reduces co-ordination and balance, making it dangerous to drive or use machinery. Cannabis can affect memory and the ability to think logically. Other common immediate effects include increased heart rate, low blood pressure, faintness, and reddened eyes. There also can be a hangover effect like drowsiness and poor co-ordination that lasts for several hours.

Marijuana cigarettes have more tar than tobacco. Cannabis users thus run an increased risk of respiratory illness such as lung cancer and chronic bronchitis. This risk is increased because marijuana smokers often inhale deeply, and hold the smoke in the lungs longer, to increase the effects of the drug. Cigarette smokers who also smoke cannabis have an even greater risk of respiratory disease.