What Is Melasma? 20 Hidden Reasons That Trigger Spots

Prepared by Pharmacist Berfin Işık. Pharmacist, dermocosmetics, and active ingredient expert. This content is for informational purposes only and does not substitute for medical advice.

Melasma is a complex hyperpigmentation condition that is not resolved by simply applying sunscreen or using a spot treatment cream; it is directly triggered by the body's internal imbalances and environmental factors. Although it is often known only as "sun and pregnancy spots," there are many hidden triggers in the background that constantly activate melanocytes (pigment-producing cells). A recent review reveals that melasma is a multifactorial process operating at the epidermal, basal membrane, and dermal levels (vascular changes, mast cells, senescent fibroblasts). In this guide, we address 20 triggers that fuel melasma as systemic (internal) and topical (external) exposures with scientific evidence.

What is Melasma and Why is it Not One-Dimensional?

Melasma is a chronic pigment disorder that typically manifests as symmetrical light brown to gray-brown spots and patches on sun-exposed areas of the face (cheeks, upper forehead, upper lip). Viewing it as "just sun spots" is the most common mistake in treatment; because melasma is a condition where hormonal, genetic, vascular, and environmental components all play a role. Due to this multifactorial structure, expecting a "permanent solution" with a single product is unrealistic; success requires systematically eliminating the triggers layer by layer.

How Does Melasma Form on the Skin?

At the core of melasma are overactive melanocytes. When stimulated, these cells activate tyrosinase, the rate-limiting enzyme for pigment production, and MITF, the master regulatory transcription factor, thereby increasing melanin synthesis. The melanin produced is transferred to keratinocytes, forming dark patches on the surface. In melasma, the basal membrane between the epidermis and dermis is also damaged; this leads to pigment "dropping" into the dermis, making the spot more stubborn. Increased blood vessels and mast cells in the dermis also secrete factors that stimulate melanocytes, contributing to the condition. An important detail: this process is triggered not only by ultraviolet (UV) light but also by visible light and heat.

1. Systemic (Internal) Triggers: 10 Hidden Causes

These triggers stimulate melanocytes through the body's internal hormonal, metabolic, and nutritional processes. In a case-control study, melasma patients showed significantly higher rates of family history (39%), oral contraceptive use (81%), and thyroid dysfunction (20.3% vs. 8.4% in the control group).

• 1. Chronic stress and elevated cortisol: Cortisol and CRH (corticotropin-releasing hormone) released during stress bind to receptors on melanocytes, stimulating melanin production. This is the mechanism behind the observation "my spots darken when I'm stressed."
• 2. Estrogen dominance and birth control pills: Estrogen increases pigment production through estrogen receptors on melanocytes. Therefore, melasma is triggered not only during pregnancy but also by estrogen-containing birth control pills and hormonal IUDs.
• 3. Thyroid dysfunction (especially Hashimoto's): Thyroid dysfunction is significantly more common in melasma patients compared to control groups. Imbalance in thyroid hormones enhances the skin's pigment response to stimuli.
• 4. Gut dysbiosis: Imbalance in gut flora (dysbiosis) increases systemic inflammation; these inflammatory signals, reaching the skin via the bloodstream, direct melanocytes to produce more pigment.
• 5. Liver burden and estrogen metabolism: The liver metabolizes and eliminates excess estrogen from the body. When this detoxification capacity is strained, systemic estrogen accumulates, fueling hyperpigmentation.
• 6. Insulin resistance: High insulin levels elevate IGF-1 levels; IGF-1 is a powerful trigger that stimulates melanocyte proliferation and melanin synthesis. Therefore, metabolic health is an integral part of melasma management.
• 7. Nutritional deficiencies (zinc, iron, B12): In a case-control study, serum zinc levels in melasma patients were found to be significantly lower than in controls (zinc deficiency in 45.8% of patients). Iron and B12 deficiencies also reduce the skin's repair and antioxidant capacity, exacerbating the condition.
• 8. Heavy metal accumulation: Heavy metals like lead and mercury increase cellular oxidative stress; melanocytes produce more pigment as a protective response.
• 9. Photosensitizing systemic medications: Some antiepileptic and psychiatric medications increase the skin's sensitivity to light, aggravating melasma. Decisions regarding medication changes must always be made with a doctor.
• 10. Sleep disorders and melatonin: Melatonin is one of the body's most powerful internal antioxidants. Insufficient sleep weakens the skin's nighttime repair capacity and resistance to oxidative stress, paving the way for hyperpigmentation.

2. Topical and Environmental (External) Triggers: 10 Hidden Causes

These triggers are physical and chemical agents that directly contact the skin or to which the skin is externally exposed. The two most critical topics are visible light and heat.

• 11. Visible light (HEV / blue light): Not only sun (UV); blue light emitted from screens and LED sources also triggers pigmentation. The Opsin-3 (OPN3) receptor in melanocytes detects blue light; this activation, via a calcium-dependent pathway, increases tyrosinase activity, leading to prolonged and stubborn pigmentation, especially in darker skin tones.
• 12. Infrared light (IR) and heat exposure: Ovens, hair dryers, saunas, hot showers, and hot environments dilate blood vessels in the skin, indirectly stimulating melanocytes. In this respect, melasma is not only a light-sensitive condition but also a heat-sensitive one. For protection during summer, you can check our summer skincare guide.
• 13. Phototoxic ingredients and perfumes: Some citrus-derived essential oils (bergamot, lemon, orange) can cause a phototoxic reaction when applied to the skin and exposed to the sun; these micro-burns return as spots.
• 14. Aggressive exfoliation and peeling: Uncontrolled high-percentage peels, harsh scrubbing, and loofahs damage the barrier, initiating an inflammatory response and adding post-inflammatory hyperpigmentation (PIH) to melasma.
• 15. Incorrect sunscreen use: For melasma, not only SPF but also broad-spectrum (UVA/PA) and visible light protection are necessary. A randomized study showed that sunscreens containing iron oxide (tinted), which block visible light, significantly improved melasma compared to UV-only protective creams. For the right choice, review our sunscreen selection criteria.
• 16. Air pollution and particulate matter (PM2.5): Micro-particles in the air create free radical damage, increasing oxidative stress and consequently pigmentation.
• 17. Incorrect laser and device applications: Applying overly aggressive, high-energy lasers to melasma-affected skin can cause a "rebound" effect, making the spots darker than before. For proper post-procedure care, refer to our post-laser care guide.
• 18. Mechanical hair removal trauma (waxing, threading): Hair removal with waxing and threading on the face can lead to micro-inflammation in hair follicles, fueling melasma on the upper lip and cheeks.
• 19. Sulfates and harsh cleansers: Aggressive surfactants like SLS/SLES weaken the skin's lipid barrier; a compromised barrier leaves the skin more vulnerable to UV, blue light, and pollution. Our skin barrier guide provides guidance for barrier repair.
• 20. Unlicensed "miracle" spot creams: Illegal creams containing high amounts of mercury or uncontrolled hydroquinone are dangerous. Long-term hydroquinone misuse can lead to exogenous ochronosis, a condition where the skin turns blue-black and is difficult to reverse.

Overview of Trigger Groups

Trigger Group	Dominant Mechanism
Hormonal (estrogen, thyroid, pregnancy)	Increased melanin synthesis by stimulating melanocyte receptors
Visible / blue light (HEV)	Opsin-3 activation → increased tyrosinase → prolonged pigment
Heat and infrared (IR)	Melanocyte activation via vascular dilation and dermal stimulation
Barrier damage (aggressive care, sulfates)	Addition of post-inflammatory hyperpigmentation (PIH)
Metabolic / nutritional (insulin, zinc)	Increased oxidative stress and melanocyte sensitivity
Toxic topicals (mercury, excessive hydroquinone)	Melanocyte toxicity and risk of exogenous ochronosis

The Right Approach to Melasma Management

Success in melasma requires a multifaceted strategy, not just a single spot-lightening cream. The priority is protection: both UV and visible light should be blocked with a broad-spectrum, preferably iron oxide-containing tinted sunscreen; heat sources should be avoided. A clear (untinted) sunscreen alone cannot adequately block visible and blue light; therefore, using a tinted sunscreen containing iron oxide or adding a tinted layer over a clear product is essential for melasma. The second step is gentle care: always treat the skin like "very delicate fabric," avoiding aggressive exfoliation and harsh cleansers. The third step is tyrosinase inhibitors: proven actives like azelaic acid, alpha-arbutin, vitamin C, and systemic/topical tranexamic acid suppress pigment production. A meta-analysis showed that tranexamic acid (especially via intradermal and oral routes) significantly reduced melasma severity. You can find all actives and the tyrosinase mechanism in our spot and hyperpigmentation guide, and details on tranexamic acid in our tranexamic acid guide. Remember that results are gradual and require patience.

Medicblu Products Suitable for Melasma

Tone-Evening and Spot Actives

Daily care options that target tyrosinase and suppress pigment production:

Professional Night Depigmentation

Options for intensive night care that evens skin tone, to be used under expert supervision:

Tinted (Iron Oxide) Sunscreens: Visible Light Shield for Melasma

Clear sunscreen alone is not enough for melasma; only tinted formulas containing pigment (iron oxide) can block visible and blue light. If you use a clear SPF, adding a tinted protective layer significantly increases its effectiveness.

Frequently Asked Questions

Why doesn't melasma go away, can it be treated completely?

Melasma is a chronic and recurring condition; it is not accurate to say that it "disappears completely and permanently." However, when triggers (sun, blue light, heat, hormonal factors) are controlled and supported with appropriate active ingredients, it can significantly lighten and be kept under control. It may recur if protection is relaxed.

Which sunscreen should I use for melasma?

High SPF alone is not enough; broad-spectrum (UVA/PA protection) and visible light protection are essential. Tinted sunscreens (containing iron oxide) are especially recommended for melasma as they also block blue light and should be reapplied throughout the day.

Is clear sunscreen sufficient for melasma?

Generally not. Although clear formulas block UV, they cannot adequately block visible and blue light on their own. The most effective approach is to use a tinted protective product containing iron oxide or to add a tinted layer (BB, cushion, tinted SPF) over a clear product.

Do harsh peeling or waxing at home worsen melasma?

Yes. Aggressive exfoliation, harsh rubbing, and mechanical traumas such as facial waxing/threading can trigger post-inflammatory hyperpigmentation (PIH), darkening melasma. Gentle care is essential for melasma-prone skin.

Why are unregulated spot creams dangerous?

Illicit creams can contain high levels of mercury or uncontrolled hydroquinone. Long-term misuse of hydroquinone carries the risk of exogenous ochronosis, where the skin develops a permanent blue-black discoloration. These products should be avoided, and treatment should be planned under expert supervision.

Conclusion

Melasma is a multifaceted condition where external exposures like sun, blue light, and heat intersect with internal hormonal and metabolic factors. The key to success is to consider internal balance, protect the skin from heat and visible light with tinted sunscreens, avoid aggression, and work patiently with proven tyrosinase inhibitors. You can benefit from our free skin care consultation to create a personalized protocol.

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References

1. Ali L, Al Niaimi F. Pathogenesis of Melasma Explained. Int J Dermatol. 2025;64(7):1201-1212. PMID: 40022484 · DOI: 10.1111/ijd.17718
2. Regazzetti C, Sormani L, Debayle D, et al. Melanocytes Sense Blue Light and Regulate Pigmentation through Opsin-3. J Invest Dermatol. 2018;138(1):171-178. PMID: 28842328 · DOI: 10.1016/j.jid.2017.07.833
3. Castanedo-Cazares JP, Hernandez-Blanco D, Carlos-Ortega B, et al. Near-visible light and UV photoprotection in the treatment of melasma: a double-blind randomized trial. Photodermatol Photoimmunol Photomed. 2014;30(1):35-42. PMID: 24313385 · DOI: 10.1111/phpp.12086
4. Rostami Mogaddam M, Safavi Ardabili N, Iranparvar Alamdari M, et al. Evaluation of the serum zinc level in adult patients with melasma. J Cosmet Dermatol. 2018;17(3):417-422. PMID: 29131489 · DOI: 10.1111/jocd.12392
5. Chen LY, Kang YN, Hoang KD, et al. Intradermal Injection of Tranexamic Acid for the Treatment of Adult Melasma: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Facial Plast Surg Aesthet Med. 2025;27(4):305-312. PMID: 39574359 · DOI: 10.1089/fpsam.2024.0187
6. Beaumet M, Haudecoeur R. Hydroquinone causes exogenous ochronosis through tyrosinase catalytic activity and highlights the need for genuine human tyrosinase inhibitors. Br J Dermatol. 2025;193(5):817-818. PMID: 40795149 · DOI: 10.1093/bjd/ljaf315