So You’ve Been Tear-Gassed: A Doctor’s Eye View

Chances are, as you’re sitting there struggling to breathe, your eyes in pain and your chest feeling like it’s on fire, you have some questions.

So you’ve just been tear gassed. Chances are, as you’re sitting there struggling to breathe, your eyes in pain and your chest feeling like it’s on fire, you have some questions.

I’m a doctor. Here’s a scientific take on what you need to know.

What to do

The best thing you can do to treat the effects of tear gas is to get away from the contaminated area as soon as possible.

Recovery is usually complete 30 minutes after you’re out in fresh air. Look for a well-ventilated area with free flowing air. Blowing air into your eyes can help, but putting an isotonic fluid, or just water, is also recommended.  Wash your skin with soap and lots of flowing water.

If you’re helping someone who’s been tear-gassed, make sure to protect yourself from contamination: you want to use gloves, goggles and face-airway protections.

Remember that homemade tear gas masks have not proven to work, and may make things worse.

Despite what you may have heard, the use of bandanas soaked in various things (water, vinegar, cider vinegar, lemon juice or antacid) has not been scientifically tested and, contrary to popular belief, most do not work against tear gas or pepper spray. A single low-quality study did conclude that topical application of antacids for capsaicin-induced pain is effective, particularly in early treatment of exposure.

Contaminated clothing should be removed and sealed. Wash it and rinse it several times afterwards with conventional washing detergent. Use cool water only, since hot water may cause residual CS to vaporize and contaminate nearby objects and/or people.

Any other management should be left to trained healthcare professionals. If something is not normal, please, contact any health service immediately. Read the recommendations by Prof. Mónica Krauter on Twitter.

Will it kill me?

You may be wondering: how bad for my health is the (non-lethal) chemical weapon that’s just been sprayed on me, really? Here’s what we know.

Tear gas and pepper spray have been widely used in crowd control throughout the world for many decades.

The thing that’s making your lungs feel like they’re on fire is probably CS gas, named after the two chemists who first synthesized it in the 1920s, Corson and Stoughton (the chemically inclined might prefer to call it O-chlorobenzylidene). CS is a fine, white, dusty powder that smells kind of like black pepper.

Alternatively, you may be choking on capsaicin, another chemical widely used as the principal compound in pepper sprays. Less commonly, there may be chloropicrin and a variety of chloroacetones, but for brevity we’ll leave those out. Usually it’s CS.

According to a review in the British Medical Journal, “in the main, the medical literature supports the safety of CS gas.” In small doses, CS acts within seconds, producing severe local reactions when it comes in contact with your mucous membranes and skin. Although the CS molecule contains certain cyanide-like functional groups, it doesn’t actually convert to cyanide, though that probably helps explain some of its effects.  

Longer term, there really isn’t any good research — and there probably won’t ever be: you can’t very well have a randomized controlled trial to determine the long-run effects of tear gas. There’s certainly a chance that tear gas exposure has long term effects we just don’t know about. Think of it this way: if tear gas does have nasty long term effects, we wouldn’t know about them. On the other hand, even in the hyper-litigious United States, no lawsuit for damages has ever been successful.

What Tear Gas Does

  • CS effects set on quickly (10-30 seconds) and pass away quickly (15-45 minutes), but the time for complete recovery is unknown. Some studies mention that delayed effects may appear after eight hours to one week or more after exposure. It’ll depend on the concentrations, the length of exposure, and the person.
  • CS, both in its spray and smoke delivery forms, adheres to surfaces, skin and mucous membranes. You can get recontaminated by touching or being in contact with surfaces, clothing or things.
  • CS and Capsaicin can irritate you even in very low doses after exposure.


  • CS and Capsaicin are commonly known as lacrimators. They stimulate tear production. They produce an intense irritation in the eyes, involuntary closing of the eyelids and swelling. In effect they can blind you temporarily.
  • Symptoms are more severe in people who wear contact lenses.
  • A few long term studies confirm that continuous contamination by CS may cause cataracts, vitreous hemorrhage (hemorrhage inside the eye), traumatic optic neuropathy (chemical trauma that affects the optic nerve), among other complications.
  • Corneal damage has been described.

Respiratory System

  • CS stuffs up your nose, or gives you a red, swollen, runny nose.
  • CS in your mouth has a bitter, burning, acidic taste just before reaching your throat.
  • Once in your throat, it affects the larynx, trachea and lungs.
  • CS then makes the secretions in your respiratory system go crazy, and can cause your bronchi to close. Your chest may hurt. Lots of coughing will usually result.
  • CS makes some people cough up blood. It may cause chemical pneumonitis (inflammation of lung tissue.) In some cases it can give you a pulmonary edema — a sudden build up of fluids in the lungs. That’s a proper medical emergency, but it’s very rare.


  • CS on your skin produces a burning sensation, pain, skin edema, itching and sometimes a redness of the skin or mucous membranes.
  • Prolonged contact worsens the effects and can result in chemical burns.
  • Wet skin and wet clothes also worsen the effects of CS.
  • Dermatitis and blistering are also described after CS exposure.

Gastrointestinal System

  • CS causes loss of appetite, nausea, vomiting, hematemesis (vomiting of blood) and even diarrhea in some cases.
  • Liver damage has been described (acute hepatocellular changes and liver enzyme alterations).

Central Nervous System

  • CS may affect the nervous system indirectly, producing disorientation, dizziness, anxiety, fainting and loss of consciousness.
  • There are no conclusions about its effects on people with epilepsy, but convulsions have been reported.
  • Traumatic brain injury might occur secondary to tear gas shell impact.

Other Systems

  • Tachycardia and other heart arrhythmias have been described after contact with CS.
  • Increase in blood pressure may occur in hypertensive patients.
  • Peripheral nerve damage has been reported.
  • Vascular and musculoskeletal injuries might occur secondary to tear gas shell impact.
  • Individuals with other chronic conditions (diabetes, heart disease, arthritis, thyroid disease, multiple sclerosis, allergies) are at heightened risk for other complications, particularly aggravation of the pre-existing diseases, after tear gas exposure.
  • There is no evidence to support that CS gas is carcinogenic (produces cancer) or teratogenic (disturbs the development of the embryo or fetus during pregnancy).

Children and the Elderly

  • In developed countries, the effects of CS and other tear gases on fragile groups such as children and the elderly are not registered or reported, mostly because the security forces that use CS in crowd control -usually- follow correct-use guidelines and recognize international law and conventions. On the elderly there is a very low risk of acute angle-closure glaucoma.

If you want to continue reading, check out a couple of interesting articles:

  1. Hill A, Silverberg N, Mayorga D. Medical Hazards of the Tear Gas CS A Case of Persistent, Multisystem, Hypersensitivity Reaction and Review of the Literature. Medicine. 2000;79(4):234-240.
  2. Kim-Katz S, Anderson I, Kearney T. Topical antacid therapy for capsaicin-induced dermal pain: a poison center telephone-directed study. The American Journal of Emergency Medicine. 2010;28(5):596-602.
  3. Park S, Chung E, YI G. A Study for Health Hazard Evaluation of Methylene Chloride Evaporated from the Tear Gas Mixture. Safety and Health at Work. 2010;1(1):98-101.
  4. Rothenberg C, Achanta S, Svendsen E, Jordt S. Tear gas: an epidemiological and mechanistic reassessment. Annals of the New York Academy of Sciences. 2016;1378(1):96-107.
  5. Wani M, Lone G, Singh S, et al. Vascular injuries caused by tear gas shells: surgical challenge and outcome. Iranian journal of medical sciences. 2011; 36(1):14-17.
  6. Worthington E, Nee P. CS exposure–clinical effects and management. Emergency Medicine Journal. 1999;16(3):168-170.