The link between UV exposure and skin ageing is well-established. Less understood — but clinically significant — is the contribution of heat itself, independent of UV radiation, to accelerated skin ageing. For Indian patients experiencing ambient temperatures of 40-45°C for months at a time, this is a year-round dermatological concern, not a seasonal footnote.

How Heat Ages Skin

Infrared radiation — the heat component of sunlight — penetrates deeper into the skin than UV, reaching the dermis where collagen and elastin are produced and maintained. Research demonstrates that infrared A radiation (IRA) at dermal temperatures achievable during significant heat exposure activates matrix metalloproteinases (MMPs) — enzymes that degrade collagen and elastin. This collagen degradation pathway is independent of and additive to the UV-mediated damage from UVB and UVA. The practical implication: patients who protect themselves from UV but spend extended time in high heat environments — in vehicles, outdoors, in non-air-conditioned spaces — are still accumulating dermal collagen damage.

Heat, Sweating, and the Skin Barrier

Chronic sweating in Indian summer creates its own skin challenges beyond heat rash. Repeated wetting and drying of the skin surface from sweat cycling disrupts the skin barrier — the constant hydration-dehydration stress degrades the lipid matrix of the stratum corneum over time. Salt and lactic acid in sweat are mild irritants that cause cumulative low-grade inflammation, particularly in skin fold areas and around the eyes.

Practical Protection Against Heat Ageing

Antioxidant-rich skincare — vitamin C, vitamin E, niacinamide — neutralises free radicals generated by infrared radiation and heat stress. Consistent sunscreen use (which filters some infrared alongside UV, particularly formulations containing iron oxides or zinc oxide) provides partial protection. Minimising prolonged heat exposure during peak afternoon hours (11am-4pm) reduces cumulative thermal stress on the skin. And maintaining a consistent hydration and barrier repair routine throughout summer counteracts the barrier disruption from chronic sweating. This is an area where year-round diligence produces meaningfully better skin health outcomes over decades.

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— Dr. Nishita Ranka | Consultant Dermatologist | Dr. Nishita’s Clinic for Skin, Hair & Aesthetics, Hyderabad