I’m going to quote at length from Riot Medicine because I keep seeing questionable or outright wrong shit about how to treat riot control agents like pepper spray and tear gas, especially if it gets in the eyes. The author is an experienced anarchist street medic who has also expressed frustration with this shit. I’ve slightly reformatted the passages below to make linking citations easier.
Because of the prevalence of RCAs at demonstrations, medics have invented and deployed their own homegrown treatments and remedies. Many of these have been shown to be ineffective, and some are actually harmful. Like when administering any medication, these remedies may cause an allergic reaction on their own.
LAW. Liquid antacid and water (LAW) is a mixture of 50% liquid antacid and 50% water. In some countries, LAW is simply referred to as Maalox. LAW is an extremely popular treatment, in part because of its simplicity and the minor cooling sensation patients report when LAW is applied to the skin. Liquid antacid does not belong in the eyes, and although rare, ingredients in antacids may cause an allergic reaction. Research on pain relief provided by topical application of antacid is mixed. One study showed no significant decrease in pain for patients exposed to OC spray after applying liquid antacid [1]. Another showed statistically significant decrease in pain up to the 60 minute mark, but concluded “the difference in [pain levels] may have questionable clinical significance [2].” Anecdotal evidence supports the idea that LAW decreases pain for OC spray on the skin, but it is not recommended even if it is marginally more effective.
Baby shampoo. Baby shampoo has not been shown to be effective when used in the eyes or on the skin for treating either pepper spray or tear gas [1] [3] [4].
FAST. Fixative antacid surfactant treatment (FAST) is a pepper spray remedy originally published on It’s Going Down [5]. FAST was designed to be a more effective alternative to LAW that combined the active ingredients of antacid, sunflower lecithin, and baby shampoo. While there was some experimentation done by the creators to determine whether this treatment was effective, it lacked the rigor [to] make conclusions. More generally, research on the individual active ingredients suggests that they do not provide a statistically significant decrease in pain.
Cow’s milk. Plain cow’s milk is another common treatment for pepper spray and tear gas. Pouring milk into the eyes has risk of infection, and this is especially true on hot days where the milk will not remain refrigerated before use. The stickiness and stench of milk is another downside of using milk as a decontaminant. Most importantly, cow’s milk used as a treatment for pepper spray has not been show to have a significant effect on pain levels [1].
Oils. Mineral oil followed immediately by alcohol (MOFIBA) is an outdated treatment for pepper spray contamination that is no longer used by most medics. The treatment worked by covering small patches of skin with mineral oil to attract pepper spray, then removing it with rubbing alcohol. This was retired from use because if done incorrectly can cause additional pain over pepper spray alone. Similarly, people have used vegetable oil to wash the affected area, wiping the residue off after, and this should not be done either. Both of these methods are harmful because oil will trap the RCA against the skin.
Onion. Onions have been inaccurately reported as effective against tear gas. This belief seems to be most prevalent in the Middle East and North Africa. The reported procedure is to breath over whole or cut onions, and in particular to use onions themselves as part of improvised gas masks to mitigate the effects of inhaling tear gas. RCAs, and in particular tear gas, are lachrymators. Chopped onion releases a chemical which is also a lachrymator. Onions do not mitigate or prevent the effects of tear gas.
Vinegar. Vinegar is another commonly suggested ineffective remedy and preventative measure for tear gas inhalation. Activists suggest using it as a decontaminant on affected skin. It has been suggested to soak a bandana in vinegar then breath through it to prevent inhalation of tear gas. Like tear gas, vinegar is a lachrymator. Vinegar vapor irritates the eyes, and prolonged inhalation will irritate the lungs.
Citrus. Lemon and lime have been suggested to be used like vinegar, both as a decontaminant wash for the skin and with a bandana as a filter for tear gas. There is no evidence either of these have any effect on reducing the irritation associated with tear gas or preventing inhalation.
Hydrogen peroxide. Hydrogen peroxide is another remedy used by activists and medics to treat tear gas and pepper spray. There is no evidence that this has any effect on either, and further, it will cause additional burning sensations if it gets into the eyes or other mucous membranes. Given that pepper spray is mainly aimed at the face and tear gas affects the eyes, nose, and mouth, there is high risk of causing additional harm to the patient even if it was an effective treatment.
Lidocaine. Lidocaine in particular when used as a treatment for pepper spray has not been shown to have a significant effect on pain levels [1].
Miscellaneous. Some activists have suggested a variety of treatments such as using baking soda paste, topical analgesics, or toothpaste to treat affected areas. These are not recommended as they trap RCAs against the skin and may worsen its effects.
Riot control agents are lachrymators that are sprayed on to protesters or deployed as an aerosol. Symptoms are a burning sensation where exposed, especially the eyes, nose, mouth, and lungs. More serious symptoms like vomiting, syncope, anaphylaxis, and respiratory distress may be present as well as secondary traumatic injuries from fired cannisters. Because these are area of effect weapons, you will often end up needing to triage and treat many patients at once. Many common remedies for tear gas and pepper spray have limited clinical effectiveness, and so decontamination should only be done with water or saline. Flush the patient’s eyes and body with water or saline, and afterwards consider wrapping them in an emergency blanket if there is a risk of hypothermia.