Poison and its Classification


Poison is toxic substance that causes disturbances in organisms, usually by a chemical reaction or other activity at molecular level when sufficient amount is being absorbed by the organism.

Classification of poisons:

  1. On the basis of origin:

Poison may be:

  • Synthetic poison: Synthetic source may include various types of chemicals.
  • Natural poison: Natural poison may be of vegetable, animal or mineral origin and 
  1. On the basis of mechanism of action:

Poisons may be of following types;

1. Irritants: 

They may be inorganic, organic or mechanical irritants.

  • Inorganic irritants/substances: 

They are either metallic or nonmetallic.

Nonmetallic irritant:

Phosphorus, chloride, iodine, bromine are examples

Metallic poisons:

Copper, lead, mercury etc. are examples.

  • Organic poisons:

They are either of:

  • Animal origin: like venom of snake, scorpion, and insects etc.
  • Plant origin: like ergot, aloe, capsicum, and castor seed etc.
  • Mechanical irritant poison:

Powdered glass and diamond may sometime be used as mechanical irritant poison.

2. Corrosive poison: 

Strong acids and bases are the examples of these types of poison. They destroy the organs and tissues internally as well as externally.

Examples: Hydrochloric acid, sulfuric acid and sodium hydroxide etc. may act as poison.

3. Neurotic poison:

They as the name indicates act on the nervous system (central or peripheral) and cause toxic effects.

Examples: Sedative, hypnotics, cocaine, nuxvomica and curare

4. Cardiac poisons:

Digitalis, stropanthus, and aconite are the examples.

5. Respiratory depressants:

Poisonous gases like carbon mono oxide (CO) and coal gas are the examples of respiratory depressant poisons. The patient dies due to the poor supply of oxygen.

6. Miscellaneous poisons: 

Drugs like analgesics, antipyretics, antihistamines, and antidepressants may produce toxicity when consumed in higher doses and finally results in patient’s death.


Abid Ali @abidaliphm

Doctor of Pharmacy


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