What is the main cause of razor burn?

The main cause of razor burn is using a dull blade. When a blade is dull, it cannot effectively cut the hair, resulting in more friction and irritation on the skin's surface. This irritation can lead to the inflamed red bumps and discomfort that characterize razor burn. A sharp blade glides more smoothly across the skin, cutting hair cleanly and reducing the chance of pulling or tugging, which is often what causes the burning sensation and irritation associated with razor burn.

While using an electric razor, shaving in a hurry, and excessive use of aftershave can contribute to skin irritation in different contexts, they are not the primary triggers for razor burn. A dull blade remains the most significant factor because it directly affects the quality of the shave and the overall skin experience during and after shaving.