Why is sun exposure a concern before and after laser hair removal?

• A. Increased epidermal melanin from tanning raises PIH risk and reduces selectivity; post-treatment sun exposure increases pigment changes risk.
• B. Sun exposure has no effect.
• C. Sun exposure after treatment improves outcomes.
• D. Sun exposure only affects hair regrowth.

Answer: (A)

Sun exposure matters because lasers for hair removal rely on selective photothermolysis: they target melanin in the hair follicle while sparing surrounding skin. When the skin is tanned or has higher epidermal melanin, more laser energy is absorbed by the skin rather than the hair. This reduces treatment selectivity and increases the risk of burns and post-inflammatory hyperpigmentation (PIH). Before treatment, avoiding sun and not having a tan helps keep epidermal melanin low so the energy mainly affects the hair follicle. After treatment, the skin is more sensitive and prone to pigmentary changes during healing, so sun exposure can worsen PIH and pigment alteration. Use sunscreen and sun protection to minimize these risks.