Skip to Content

Insecticide Poisoning


Gerald F. O’Malley

, DO, Grand Strand Regional Medical Center;

Rika O’Malley

, MD, Albert Einstein Medical Center

Last full review/revision February 2019 by Gerald F. O’Malley, DO; Rika O’Malley, MD
  • Many insecticides can cause poisoning after being swallowed, inhaled, or absorbed through the skin.
  • Symptoms may include eye tearing, coughing, heart problems, and breathing difficulties.
  • The diagnosis is based on symptoms, blood tests, and a description of events surrounding the poisoning.
  • Several drugs are effective in treating serious insecticide poisonings.

(See also Overview of Poisoning.)

The properties that make insecticides deadly to insects can sometimes make them poisonous to humans. Most serious insecticide poisonings result from the organophosphate and carbamate types of insecticides, particularly when used in suicide attempts and, when accidental, in occupational settings.

  • Organophosphates include malathion, parathion, fenthion, dursban, diazinon, chlorpyrifos, and sarin. Some of these compounds are derived from nerve gases.
  • Carbamates include aldicarb, carbaryl, carbofuran, fenobucarb, and oxamyl.

Pyrethrins and pyrethroids, which are other commonly used insecticides, are derived from flowers and usually are not very poisonous to humans.

Many insecticides can cause poisoning after being swallowed, inhaled, or absorbed through the skin. Some insecticides are odorless, thus the person is unaware of being exposed to them. Organophosphate and carbamate insecticides make certain nerves “fire” erratically, causing many organs to become overactive and eventually to stop functioning. Pyrethrins can occasionally cause allergic reactions. Pyrethroids rarely cause any problems.


Organophosphates and carbamates cause eye tearing, blurred vision, salivation, sweating, coughing, vomiting, and frequent bowel movements and urination. Blood pressure can decrease. Heart rate can decrease and become erratic and seizures can occur. Breathing may become difficult, and muscles twitch and become weak. Rarely, shortness of breath or muscle weakness is fatal. Symptoms last hours to days after exposure to carbamates, but weakness can last for weeks after exposure to organophosphates.

Pyrethrins can cause sneezing, eye tearing, coughing, and occasional difficulty breathing. Severe symptoms rarely develop.


  • History of exposure to insecticides and characteristic symptoms
  • Blood tests

The diagnosis of insecticide poisoning is based on the symptoms and on a description of the events surrounding the poisoning. The diagnosis is supported if atropine, given by vein, relieves the person's symptoms. Blood tests can confirm organophosphate or carbamate poisoning.


  • Removal of contaminated clothing and washing of skin
  • Treatments to support breathing and heart function
  • Atropine given by vein

Anyone with symptoms of organophosphate poisoning should see a doctor. If an insecticide might have come into contact with the skin, clothing is removed and the skin is washed. Caregivers should avoid contaminating themselves while providing care.

Doctors monitor people for respiratory failure and give atropine and other treatments to maintain their breathing and heart function. Atropine, given by vein, can relieve most of the symptoms. Pralidoxime, given by vein, can speed up recovery of nerve function, eliminating the cause of the symptoms. Symptoms of carbamate poisoning also are relieved by atropine but usually not by pralidoxime. Symptoms of pyrethrin poisoning resolve without treatment.

More Information

  • American Association of Poison Control Centers; 1-800-222-1222

Drugs Mentioned In This Article

Generic Name Select Brand Names
atropine ATROPEN

© 2020 Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Merck Manual Disclaimer