Why Melasma Gets Worse with Heat and What You Can Do About It

Many people associate melasma only with sun exposure. However, in clinical practice, we often see patients whose melasma worsens even when they are careful with sunscreen and avoid direct sunlight. One of the most overlooked contributors to melasma flare-ups is heat.

At Derm School, we focus on helping you understand how pigmentation behaves in real life, not just in theory. Melasma is a condition that responds to multiple internal and external triggers, and heat is one of the most important ones to recognise, especially in warmer climates.

Understanding Melasma Beyond Sunlight

Melasma is a form of chronic hyperpigmentation where pigment-producing cells become overactive. While ultraviolet radiation is a well-known trigger, melasma does not depend on sunlight alone.

Factors that influence melasma include:

• Ultraviolet and visible light exposure
• Hormonal changes
• Genetics
• Skin inflammation
• Heat

Any sustained rise in skin temperature can influence how pigment cells behave.

How Heat Affects Pigment Cells in the Skin

Increased Melanin Production

Pigment-producing cells become more active when skin temperature rises. Heat increases the activity of enzymes involved in melanin production, leading to darker and more persistent pigmentation.

This is why many patients notice worsening melasma during summers, even if they are mostly indoors.

Heat-Induced Inflammation

Heat can cause low-grade inflammation in the skin, even without visible redness or burning. This inflammation sends signals that stimulate pigment production.

Melasma behaves similarly to post-inflammatory hyperpigmentation, where inflammation encourages pigment to settle deeper and last longer.

Because heat also increases oxidative stress in the skin, antioxidant support can be helpful in melasma management. Alongside sunscreen and barrier care, incorporating antioxidant formulations such as Dr. Su GlutaGlow may help support skin resilience as part of a comprehensive approach.

Increased Blood Flow to the Skin

Heat causes blood vessels to dilate. This increased circulation brings more signalling molecules to melanocytes, further encouraging pigment production. This vascular component helps explain why melasma often appears patchy and why it tends to relapse easily.

Everyday Sources of Heat That Can Worsen Melasma

Many people are surprised to learn that heat exposure often happens indoors. Common triggers include:

• Cooking near gas stoves
• Long hot showers or steam
• Blow drying hair close to the face
• Intense workouts without cooling breaks
• Sitting near windows during the day
• Warm and humid environments

Even without sun exposure, repeated heat exposure can gradually deepen pigmentation.

Why Sunscreen Is Still Essential but Not Enough Alone

Sunscreen remains the foundation of melasma management. It protects against ultraviolet rays and, in some formulations, visible light as well.

However, sunscreen cannot block heat. This is why melasma may still worsen despite good sun protection practices. In such cases, management needs to extend beyond sunscreen to include heat awareness and skin-calming strategies.

Practical Steps to Manage Heat-Triggered Melasma

Choose Comprehensive Sun Protection

Use a broad-spectrum sunscreen daily. For melasma-prone skin, formulas that also protect against visible light are especially helpful. Apply generously and reapply when needed, particularly if sweating.

Reduce Unnecessary Heat Exposure

Small daily changes make a significant difference:

• Use lukewarm water for cleansing
• Avoid prolonged hot showers and steam
• Allow your skin to cool after exercise before applying products
• Limit direct heat exposure from appliances when possible
• Cooling the skin helps reduce inflammatory signals that drive pigmentation.

Be Cautious with Heat-Based Skin Treatments

Procedures that generate heat in the skin should be approached carefully in melasma-prone individuals. Treatment planning should be conservative, gradual, and focused on long-term pigment stability rather than quick results.

Support the Skin Barrier Consistently

A healthy skin barrier reduces inflammation and improves pigment control. Gentle cleansing, adequate moisturisation, and barrier-supportive skincare help the skin tolerate environmental stress better, including heat.

How to Structure Your Routine in Hot Weather

If melasma worsens in summer or heat-prone environments, your routine needs to adapt, not just remain gentle.

A practical structure looks like this:

Morning

• Broad-spectrum sunscreen with visible light protection
  
  
• Pigment-regulating treatment if prescribed
  
  
• Minimal layering to reduce heat trapping
  
  

Midday

• Reapply sunscreen when outdoors
  
  
• Avoid prolonged exposure to direct heat
  
  
• Cool the skin gently before reapplying products after sweating
  
  

Evening

• Use targeted pigmentation treatments consistently
  
  
• Avoid over-exfoliation in hot weather
  
  
• Support skin recovery with antioxidants if recommended
  
  

Melasma improves when trigger control and treatment work together. Managing heat without treating pigment slows progress. Treating pigment without managing heat leads to relapse.

Consistency is more important than intensity.

Setting the Right Expectations

Melasma is a chronic condition. It tends to respond slowly and requires consistent management rather than short-term fixes. Heat is one of the reasons melasma can return even after improvement.

Understanding your triggers and managing them daily allows better control over time and reduces the risk of flare-ups.

Derm School Takeaway

Melasma is not influenced by sunlight alone. Heat plays a significant role in activating pigment cells and sustaining pigmentation.

Effective melasma care requires controlling triggers and using targeted treatment consistently. Sun protection, heat awareness, inflammation control, and pigment-regulating strategies must work together for long-term stability.

At Derm School, our goal is to help you make informed, practical choices that support your skin in the long run.