Based on trials by many street medics, this is one recommendation for exposure to pepper spray, especially for the mucous membranes (eyes, nose, mouth, genitalia)
L.A.W. is a solution of half liquid antacid and half water. This only applies to aluminum hydroxide or magnesium hydroxide based antacids such as Maalox (plain or mint). Please note that simethicone based antacids have NOT used in trials so far, and therefore are not recommended (however, simethicone as a secondary ingredient in Maalox has not been shown to cause harm.) Products like milk of magnesia and pepto bismol are NOT recommended.
Not all action medical folks use the same protocol. Some action medics only treat with an eye flush or eye wash of water or saline. This picture demonstrates and eye wash. Others use L.A.W. alone to flush the eyes. The trend has been toward using water (sometimes with salt in it to mimic tears) followed by several drops of L.A.W. or a spritz of L.A.W. with a spray bottle. This approach reduces the need for industrial medicines, demystifies the treatment, and makes it easier for protesters in general to learn how to treat themselves. An emphasis on using water reduces the chance that someone might think that they can't treat pepper spray victims because they don't have L.A.W. however, if water isn't available L.A.W. is the primary treatment. See the eye flush page to learn about the best technique for flushing eyes.
L.A.W. is also used to treat the skin; or as a mouth rinse, as long as the victim is alert and able to manage her/his own airway.
During cold weather, do your best to keep yourself and the victim dry.
A University of California San Francisco-based study has found that topical application of antacids " for capsaicin-induced pain is effective, particularly in early treatment of exposure to refined capsaicin."