Go au natural. The last thing you want to do to treat underarm razor bumps is to cause further irritation with follow-up shaving. If you can manage, skip a few days of shaving to let the hair grow in naturally.
Hold the antiperspirant. Antiperspirants work by clogging your sweat glands with aluminum ions. If your bumps are caused by ingrown hairs, avoid clogging up even more follicles by skipping the antiperspirant for a few days.
Don't touch. Razor bumps might resemble the pimples you can't help but pop when they show up on your face, but they are actually ingrown hairs, and pinching or prodding them with needles only increases the risk of pushing bacteria into the follicle. Avoid infections by remaining hands-off.
Scrub down. A gentle exfoliating scrub lightly scrapes away the thin layer of skin that keeps ingrown hairs stunk in those painful bumps. Don't get too aggressive; too much rubbing only causes further irritation.
Tame the itch. An over-the-counter anti-itch cream reduces inflammation and provides some relief form the painful itching. Follow up with an anti-bacterial cream to ward off infections.
Cool off with an ice pack. Wrap an ice pack in a wash cloth and hold it under your armpit for 2 to 5 minutes to reduce redness and swelling if you are under a time crunch.
Let them breathe. Avoid shirts or dresses with beaded detail under the arms or made from materials that hold sweat against your underarms. Swap out wool sweaters for loose cotton T-shirts while your underarms heal.
Prevention is the best way to deal with underarm razor burn. Shave with sharp razors and ample shaving gel to prevent irritations.
If your problem is persistent, talk to you doctor about a potential bacterial infection that requires medication.