Hair smoothing, also known as hair straightening or relaxing, can have the following side effects: Scalp irritation: Hair smoothing products contain chemicals that can cause irritation, itching, and redness on the scalp. Allergic reactions: Some people may have an allergic reaction to the chemicals in hair smoothing products, causing symptoms such as itching, redness, and hives. Damage to hair: The chemicals used in hair smoothing can weaken and damage hair, leading to breakage, split ends, and dryness. Loss of hair: In some cases, hair smoothing can cause hair loss. Inhaling harmful fumes: The chemicals used in hair smoothing can produce fumes that can be harmful if inhaled. It's important to choose a reputable hair stylist who uses quality products and to follow the instructions carefully to minimize the risk of side effects. Before undergoing hair smoothing, it's also a good idea to perform a patch test to check for any potential allergic reactions. If you experience any side effects, stop using the product.