Pyrethrin is the general term for the six insecticidal compounds in pyrethrum, or Chrysanthemum flower resin, according to "Critical Care and Toxicology," by Jeffrey Brent. These extracts from the Chrysanthemum flower are used in insecticides and are found in bug bombs and lice medicines. Pyrethrins can get into your system by ingestion, inhalation or skin contact, though they're not well absorbed via skin. Risk to humans is low, but they can cause adverse effects.
Inhalation Effects
If you inhale pyrethrins you may suffer difficulty breathing, wheezing, coughing, shortness of breath, runny or stuffy nose or chest pain, according to the National Pesticide Information Center, or NPIC. Severe reactions are rare, but cases of anaphylactic reactions, some of which were fatal, have been reported, notes the California Department of Health Services, or CDHS. Inhaling pyrethrins also has caused hypersensitivity pneumonitis in rare cases. Hypersensitivity pneumonitis is a lung disease caused by repeated inhalation of chemicals or other antigens, reports the University of California Medical Center in San Francisco. In essence, your body's immune system reacts to the antigens, causing your lung to become inflamed. This can sometimes lead to lung scarring.
Topical Effects
If you have skin contact with pyrethrins, you may experience itching, a rash, or blisters, advises NPIC. You should not use louse medications that contain pyrethrins on skin that is inflamed, informs Drugs.com. If your skin gets irritated after using such medicines, you should contact your doctor. Symptoms of contact dermatitis are the most common reaction to pyrethrin exposure, according to CDHS. The effects on your skin may be caused by irritant or allergenic effects of pyrethrins, or by irritation due to petroleum distillates used in formulating products with pyrethrins. Contact dermatitis may be extremely uncomfortable, but is not life-threatening or contagious, according to the Mayo Clinic. In general, pyrethrins are considered non-toxic, according to the University of Maryland Medical Center.
Lice Formulation Side Effects
Using medication with pyrethrins combined with piperonyl butoxide, a common topical formulation for treating lice, can bring on sudden sneezing attacks, advises Drugs.com. It can also cause side effects that resemble those of inhaling pyrethrin, including difficulty breathing, wheezing or a runny nose. You need to consult your doctor immediately if you experience these side effects.
References
- "Critical Care and Toxicology;" Jeffrey Brent; 2005
- University of Maryland Medical Center: Bug Spray Poisoning
- PubMed: Croatian Institute for Medical Research and Occupational Health journal "Arhiv za higijenu rada i toksikologiju;" Health effects of pyrethrins and pyrethroids; J. Macan; 2006
- National Pesticide Information Center: Pyrethrin
- Drugs.com: pyrethrum extract and piperonyl butoxide (Topical route)
