Consumption of large or excessive amounts of caffeine can lead to headaches and mental irritability, insomnia, restlessness, dizziness, trembling, diarrhoea, shortness of breath and anxiety. Alcohol is a depressant drug. It acts on the nervous system like an anaesthetic. Social, cultural and psychological factors combine to determine how the drinker then behaves. Euphoric, amorous, weepy or aggressive behaviour may be exhibited, as alcohol lessens the learned restraints.
Drinkers can die from fatal overdoses of alcohol through depression of breathing.
Disease and failure of these body organs and systems can lead to death. The effects of cannabis are even more variable than most other psychoactive drugs. Cannabis is a unique drug. It defies attempts at precise pharmacological classification since its effects are so various. Under different conditions it can act as a stimulant, as a sedative, as an analgesic or as a mildly hallucinogenic drug.