What are chemicals that have certain hallucinogenic effects on human nervous systems

Answer: Hallucinogens

Explanation:

The drugs used by the human beings that causes hallucinogenic effect on the human nervous system. it can be defined as a substance that can cause perceptual anomalies, emotions, change in thoughts, substantial subjective change.

There are many chemicals available that can cause this effect. Example: LSD (lysergic acid diethylamide), datura, morning glory seeds et cetera.