Common misconception: the sun makes acne disappear

Acne is a common skin condition primarily associated with inflammation of hair follicles and sebaceous glands. It manifests as comedones (blackheads and whiteheads), papules, pustules, and in severe cases, nodules or cysts. This condition results from a combination of factors, including excessive sebum, follicular hyperkeratinization, bacterial colonization (particularly by Cutibacterium acnes) and localized inflammation.

During adolescence, acne is caused by a hormonal imbalance leading to excessive sebum production. The excess sebum makes the skin oily and clogs the pores, triggering the formation of blackheads and the proliferation of acne-causing bacteria. Acne tends to diminish with age, but it can persist due to a hormonal disorder or skin predisposed to breakouts (oily, acne-prone, etc.).

Among the many myths and misconceptions about acne, one claims that sun exposure can make acne disappear. This belief comes from numerous personal accounts of individuals who noticed an improvement in their acne during the summer months. Indeed, in some cases, a reduction in the formation of acne lesions can be observed.

At first, moderate sun exposure can temporarily improve the appearance of acne-prone skin. Ultraviolet (UV) radiation exerts an anti-inflammatory effect, reducing local inflammation around the lesions. Moreover, the resulting tan visually conceals some redness and imperfections, giving the impression that acne is diminishing. Some studies emphasize this temporary anti-inflammatory effect of UV on acne lesions. Furthermore, sunlight stimulates the synthesis of vitamin D, which is involved in regulating the cutaneous immune system.

However, due to the dehydration following sun exposure, the skin initiates a reactive hyperseborrhea to preserve its hydration. The sebaceous glands then begin to produce more sebum. As a result, a resurgence of acne flare-ups occurs after summer, usually around September and October. This is known as the rebound effect. Prolonged or excessive sun exposure can have deleterious effects on acne. UV radiation can induce a hyperkeratinization of the hair follicles, which promotes pore obstruction and lesion aggravation. Furthermore, sun exposure induces oxidative stress in the skin, fostering a chronic inflammation that can exacerbate acne.

Therefore, it is important to warn against these side effects and to recommend appropriate photoprotection to prevent deterioration of acne-prone skin.

A study conducted in 2018 on 110 patients aged over 25 years with acne vulgaris aimed to identify the aggravating factors of this skin condition. The researchers collected detailed data on the age at onset of acne, its duration and type, family history, as well as the potential impact of diet, cosmetics, medications, and sun exposure. The results revealed that 26.4% of participants noted a worsening of their acne following sun exposure.

Acne-prone skin requires special attention because it is naturally sensitive to sunlight. This sensitivity is often caused by applying acne treatments such as retinoids or certain antibiotics, which increase the skin’s UV sensitivity. It is therefore necessary to use rigorous sun protection to prevent burns, post-inflammatory hyperpigmentation, and lesion worsening.

Thus, sunlight offers no benefit for acne; on the contrary, it may exacerbate it.

Acne-prone skin must be protected from the sun. To achieve this, it is recommended to apply sunscreens starting at SPF 30 (ideally SPF 50) depending on skin type and the duration of sun exposure. However, the sunscreen used on acne-prone skin should be labeled “non-comedogenic.” Indeed, certain ingredients in sunscreens can be comedogenic and may therefore promote the development of acne lesions and blackheads.

Even though the cream protects the skin from the sun’s harmful effects, acne-prone skin can be sensitized by anti-acne treatments. Therefore, it is recommended to limit sun exposure by staying in the shade often or by wearing protective clothing (wide-brimmed hat, long garments, etc.).

• SARKAR R. & al. Seasonal variation in acne vulgaris--myth or reality. The Journal of Dermatology (2002).

• WATSON A. & al. A systematic review of the evidence for 'myths and misconceptions' in acne management: diet, face-washing and sunlight. Family Practice (2004).

• SRIDHARAN R. & al. Factors Aggravating or Precipitating Acne in Indian Adults: A Hospital-Based Study of 110 Cases. Indian Journal of Dermatology (2018).

• KRUTMANN J. & al. Sun exposure, a relevant exposome factor in acne patients and how photoprotection can improve outcomes. Journal of Cosmetic Dermatology (2023).