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.


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  1. The Government in defense of the “People’s Revolution” assaults their own people with CS, Pepper spray and who knows what is in the Red Gas.
    History continually repeats itself.
    First there is a revolution to free the oppressed. Then the people are oppressed to protect the revolution.
    The people that protested should be proud. They also need to know that this is only the beginning.
    The cowards and thugs that think they are real soldiers will run and hide when the wall of oppression begins to crumble.
    Real soldiers have honor. Real soldiers are protectors of citizens. Real soldiers do not attack vulnerable people. Real soldiers make sacrifices for the good of the people, their freedoms and rights. Real soldiers do not steal from the hungry and poor.
    The people wearing the uniforms are thieves, murderers and thugs. Soon I hope that they will be called inmates, convicted felons or simply deceased.
    Do not pause. Increase the pressure on this criminal regime. The only way for democracy and human rights to be restored is for the criminals in power to be removed. The cost may be high. The cost of losing the battle will be much higher.
    Your cause is just and you will prevail. The government fears you individually and collectively.
    Support for the people of Venezuela is strong around the globe. You are in the hearts and prayers of people everywhere that despise tyrants and believe in individual human rights, democracy and self determination.

  2. Very nice you provide this. I am very impressed at the resolve of demonstrators against the Maduro/chavista dictatorship.When there is little or no legal path, this is clearly the absolutely necessary way forward.

    One practical comment, which may or may not be of help – You are the MD to decide!

    When we had mass anit-war demos against the Viet Nam War and similar, I got my gas training from the Viet Nam Veterans Against the War, who had been trained, obviously, in the US military.

    I recall that it was a big deal during demos to tell people — aside from keeping absolutely covered and having good gas masks and canisters when available — that depending on what the gas smelled like you could tell if it was water-based or oil-based.

    The key difference was that one smelled strongly like apple blossoms. You could aid people by flushing with water if it was the water-based type, but if it was the oil-based one, flushing with water only made things worse. In that case we’d use (if I recall correctly) a mix of water with white vinegar (not sure about that mix now). I don’t recall offhand which was which … but I do remember very clearly the two smells.

    Any veracity/usefulness to this?

    Another imperative the x-military guys taught was the principle that, in any gas attack, one should advance, not retreat, as the gas is almost always fired downwind.

  3. Some years ago my wife and I had our first scrape with the effects of tear gas when participating in a street demonstration (this at an age when one doesnt normally go thru such experiences) , as the tear gas bombs went off the crowd stampeded and almost knocked us to the ground , I was most concerned about my wife (rather slight of build) being hurt and managed to put her against a wall using my body to protect her from the press of the rushing crowd, meantime the gas started to hurt my eyes producing a burning sensation that filled my eyes with tears blinding me for about 10 minutes . After the press of the crown subdised I was dependent on my wife to move to a safer place as I was left with a deeply blurred vision….!!

    We were advised to use goggles to cover our eyes and to spread tooth paste over our exposed skin to protect it from the tear gas and to carry a small bottle of vinegar and water to use to clean ourselves when we got gas bombed ….. !! In the rush of thing however there wasnt much time to protect ourselves more from the billows of tear gas smoke as it spread towards us … !!

  4. Given the photos I’ve seen, an important question to ask would be what chemicals would be in an expired, 2 years beyond use date tear gas grenade.

  5. Good tips about Tear Gas, but doesn’t it seem somewhat complacent?

    Sounds like the population should get used to tear gas, or worse. Algo normal..

    It’s a freaking CRIME, even in Syria.

    Again, the Boiling Frog effect seems to be at work in Venezuela. People getting used to atrocities.

    • “Sounds like the population should get used to tear gas, or worse. Algo normal..”

      Yes, the population should also get used to anarchy and mob rule, with maybe some civil war in the mix. We will look back fondly on the times of tear gassing.

      • There won’t be civil war, due to the simple fact that the fight against a dictatorship that works for an occupation invading force (Cuba) isn’t a civil war, also, it’s not a war when only one side is armed (As far as we know, because we have yet to see the first chavista killed by an armed protester in these two decades)

        Poeta, it’s not about getting used to the gas or any of the other shit chavistas want to do, it’s about KNOWING what to do in these situations, chavismo has been so adept at fending off street protests because of the crass ignorance in the matter that the MUD leadership has shown so far, because their only plan to protest is “we’ll go with the white hands and they’ll simply won’t do anyhthing because they’re too embarrassed to do it”, and we have all seen the results: Hundreds of murders at the hands of the chavista hordes, thousands of kidnappings and dozens of desapparitions too, all because the MUD leadership doesn’t ever want to acknowledge that ANY PROTEST will be ambushed and beaten or shot down by those criminals, regardless if people has done anything violent or not.

        So no, chavismo doesn’t “need the protests to become violent” to excuse their repression, they WILL use violent repression because they want to scare people from protesting again, period.

  6. We got a lot of experience on tear gas at the UCV. I can certainly tell you that nothing neutralizes it but vinegar and anti-acid helps to throw couple of more rocks before you have to move out.

    A team of encapuchados will count with 4-5 members. One or two to throw back the tear gas canisters (which are very hot) those will have kitchen gloves or something for that purpose. One or two to carry whomever may get asphyxiated. You have to dry your skin at all times to avoid some of the reaction with sweat.

    The pepper ones are the worst, those resemble a rubber ball and bounce all over the place. They don’t release visible smoke so if you don’t see it bouncing then the next is a nasty surprise. Running sometimes makes it really bad so you have to hold your breath and try to get out without breathing then hope that the first intake is fresh air.

    The most dangerous thing (outside bullets and metal bolts and nuts that the police puts in their shotguns) is when the canisters land. Most canisters will split in three half way through their flight, so when there is a barrage the chances of a canister hitting someone in the cacumen are quite high.

    Some canisters land without activation with the fuse intact. Once time we flanked the PM through the School of Hydro-works at the Plaza Venezuela exit side hill. We gave them some of their own medicine…

    Encapuchado hardware kit:
    – Helmet (if possible)
    – Capucha with vinegar
    – Small towel to dry skin
    – Water or milk to drink (may not work but helps anyway)
    – Kitchen glove to throw back the canisters
    – Sturdy shoes to kick the canisters back

  7. We have to also do some research on how to treat a tear gas bomb concussion, caused by a bomb dropped from a freaking HELICOPTER ABOVE SKYSCRAPPER HEIGHT.


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