Tear Gas (and Pepper Spray)

CS and CN Structures
CS and CN Structures
capsaicin structure
Capsaicin structure


  • Chemical irritant
  • Either powder or 1% - 5% aerosol spray
  • Commonest used are
    • chlorobenzylidene-malononitrile
    • (CS after chemists Corson and Stoughton)
    • chloroacetophenone (CN or "Mace")
    • dibenzoxazepine (CR)
    • oleoresin capsicum (OC)
    • pelargonic acid vanillylamide (PAVA)
  • Pepper strength is measured in Scoville heat units
    • Green pepper = 0, pure capsaicin = 15 million units
  • Irritant effect from action of chlorine or cyanide groups
  • Immediate release of inflammatory P substance
  • Effects enhanced by heat and by high humidity
  • Rapid onset time & short duration of effects
  • Wide margin of safety between the incapacitating dose (ICt 50, the concentration (C) that causes incapacitation (I) in 50% of individuals after one minute (t=time)) and the lethal dose (LCt 50, the concentration that causes death (L) in 50% of individuals after one minute).


Clinical manifestations and potential complications
Area Clinical Potential complications Potential sequelae
Eyes Tearing, burning sensation, blepharospasm, photophobia, corneal oedema Keratitis, corneal erosion, intraocular haemorrhage Cataract, glaucoma
Resp. Severe rhinorrhoea, sneeze, cough, dyspnoea, pharyngitis, bronchitis Bronchospasm, hypoxia, delayed pulmonary oedema Asthma
CVS Hypertension Heart failure, cerebral haemorrhage
Skin Rash, oedema, erythema, blistering Irritant dermatitis, facial oedema Allergic dermatitis
GIT Buccal irritation, salivation, abdo. pain, D&V Liver toxicity  
Neuro Trembling, agitation, anxiety    



  • Medical teams should wear protection for their own safety and to prevent secondary contamination.
  • Contaminated clothes removed; eyes and affected skin surfaces should be cleaned with water.
  • For pulmonary symptoms, oxygen therapy, β2-mimetics and ipratropium aerosols may be required.
  • For pulmonary symptoms, a 24-48 hour stay in CDU may be required.
  • Remove contact lense.s
  • Irrigate eyes with saline or Diphoterine (in storage cupboard, decontamination room CUH).
  • Wash skin with soap and water or Diphoterine (in storage cupboard, decontamination room CUH).
  • Severe skin lesions - wash then topical steroids.

Content by Dr Íomhar O' Sullivan 30/08/2011. Last review Dr ÍOS 16/12/19