Very large doses of can cause respiratory depression, coma, and death.
a. hallucinogensb. depressantsc. cannabanoids

Explanation:

Death by very large doses of depressants has happened before, but death by hallucinogens or cannabanoids are not that common.

Depressants are drug that are used to calm nerves and muscles, in other words, they depress the nervous system. They are used to treat anxiety or insomnia, because the patient need to calm down and be able to rest. The short term effects are:

In addition, long term effect are:

As you can see, the long term effect on depressants are high risk, having chances to even cause death.

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