Razor bumps, also known as pseudofolliculitis barbae, are caused primarily when shaved hairs curl back or grow sideways into the skin instead of growing straight out of the hair follicle. This typically happens with curly or coarse hair that meets resistance from dead skin cells at the pore opening, causing the hair to re-enter the skin and trigger an inflammatory reaction
. Key causes include:
- Close shaving that cuts hair with a sharp pointed end, making it easier for hair to penetrate or curl back into the skin
- Shaving techniques such as using a dull razor, shaving too fast, or shaving dry skin can contribute to irritation and razor bumps
- Hair characteristics like tightly curled, coarse hair, common in people of African descent, increase the likelihood of razor bumps
- Skin folds or scar tissue can also allow hair to re-enter the skin, leading to bumps
Razor bumps differ from razor burn, which is a skin irritation caused by friction from shaving and appears as red, irritated patches immediately after shaving. Razor bumps develop a few days later as inflamed, pimple-like bumps due to ingrown hairs
. In summary, razor bumps result from hair growing back into or under the skin after shaving, causing inflammation and irritation, especially in individuals with curly or coarse hair and certain shaving habits
