The substance covered in this section
Cannabis, also known as marijuana, Indian hemp, hashish, ganja, pot, dope and grass, is made from the Indian hemp plant Cannabis sativa.
Uses and abuse
Cannabis is often abused and, in some countries, is used almost as much as alcohol or tobacco. It makes people feel relaxed and makes colours and sounds seem brighter and louder. The dried plant is made into cigarettes or put in a pipe and smoked. Sometimes it is taken with food. Some people inject it.
How it causes harm
Cannabis affects the brain.
How poisonous it is
It does not cause much harm to adults, unless it is injected. Children are likely to get signs of poisoning but usually recover.
Signs and symptoms
Effects start within 10 minutes of smoking the drug and last for about 2-3 hours. When the drug is eaten the effects start within 30-60 minutes and last for 2-5 hours. The effects are:
- usually a feeling of well-being, happiness and sleepiness, but high doses may cause fear, panic and confusion,
- fast pulse,
- the person cannot balance when standing up,
- slurred speech,
- coughing if the drug is breathed in, as when smoking cigarettes.
If the drug is injected it may cause more serious problems:
- severe headache,
- irregular breathing,
- low blood pressure,
What to do
Give first aid. If the patient is unconscious or drowsy, lay him or her on one side in the recovery position. Check breathing every 10 minutes.
A patient who is anxious or confused should be kept in a quiet, warm room.
If the cannabis was swallowed: there is no need to make the patient vomit. If the patient is fully awake, breathing normally, and not vomiting, give activated charcoal and water to drink.
A patient who has injected cannabis should be taken to hospital as quickly as possible.
Information for doctors outside hospital
If the patient is hallucinating or violent, give chlorpromazine, 50-100 mg (adult dose), intramuscularly.
If cannabis has been injected
Monitor breathing, pulse, blood pressure, temperature. Supportive care, including oxygen and mechanical ventilation, should be given as needed:
* Low blood pressure should be treated by keeping the patient lying with the feet higher than the head; intravenous fluids can be given.