The Link Between Sunlight and Melasma: Causes, Effects & Prevention

Introduction

Melasma is a common skin condition that causes dark, uneven patches of pigmentation, mainly on the face. While several factors contribute to melasma, sunlight is one of the biggest triggers. Many people with melasma notice that their pigmentation worsens during summer or after prolonged sun exposure. But how exactly does sunlight affect melasma, and what can you do to protect your skin? Let’s explore the science behind sunlight-induced melasma and the best ways to manage it.

How Sunlight Triggers Melasma

1. UV Radiation Stimulates Excess Melanin Production
Sunlight contains ultraviolet (UV) rays that penetrate the skin and stimulate melanocytes—the cells responsible for producing melanin (pigment). In people with melasma, melanocytes are already overactive, making them even more sensitive to UV rays. This leads to excess pigment production, resulting in dark patches on the skin.

2. Infrared Radiation and Heat Worsen Melasma
Besides UV rays, the heat from sunlight and infrared radiation can also trigger inflammation in the skin. This inflammation activates melanocytes, leading to worsening pigmentation. This is why people with melasma often notice that their dark spots darken during hot weather, even if they are not directly in the sun.

3. Visible Light Contributes to Pigmentation
Recent studies show that visible light, including blue light (HEV light) from the sun and digital screens, can worsen melasma. Unlike UV rays, which damage DNA, HEV light penetrates deeper into the skin and stimulates melanocytes, leading to persistent hyperpigmentation.

How to Prevent Sunlight-Induced Melasma

1. Use a Broad-Spectrum Sunscreen (SPF 50+)

• Choose a physical (mineral) sunscreen with zinc oxide or titanium dioxide, as these offer better protection for melasma-prone skin.
• Look for sunscreens that contain iron oxide, which helps block visible light (HEV light).
• Apply sunscreen every morning, even on cloudy days or indoors.

2. Reapply Sunscreen Every 2–3 Hours

• One application in the morning is not enough—especially if you are outdoors.
• Carry a sunscreen stick, powder, or mist for easy reapplication throughout the day.

3. Wear Protective Clothing & Accessories

• A wide-brimmed hat can block a significant amount of UV radiation.
• Use UV-protective sunglasses to prevent sun exposure around the eyes.
• Consider UPF-rated clothing for additional protection.

4. Use Skincare Products That Inhibit Pigment Production

• Ingredients like Vitamin C, niacinamide, kojic acid, and tranexamic acid help to reduce melanin production and fade dark patches.
• Azelaic acid and hydroquinone are effective treatments for melasma when used under dermatologist supervision.

5. Avoid Heat Exposure

• Excessive heat can trigger melasma, so try to stay cool.
• Avoid hot showers, steam rooms, and excessive sweating that can worsen pigmentation.

Conclusion

Sunlight is a major trigger for melasma because it stimulates excess melanin production, increases skin inflammation, and worsens hyperpigmentation. However, by following a strict sun protection routine, using the right skincare ingredients, and avoiding heat exposure, you can effectively manage melasma and prevent it from worsening. If you struggle with melasma, consider consulting a dermatologist for personalized treatment options.