Dermatologists are always advising patients to try to avoid spending too much time in the sun and to apply sunscreen and sun protective clothing when going outside. For the most part these recommendations are important and true as they help prevent the negative effects of excessive sunlight on a person’s skin These negative effects include increasing a person’s risk of developing different kinds of skin cancers as well as accelerated skin aging.

Heliotherapy, which literally means sun therapy, is a form of phototherapy which uses sunlight to treat skin diseases. It has been reintroduced into modern medicine as a treatment option or adjunct to treatment (on top of the dermatologist prescribed creams or medications) for certain dermatologic diseases.


In 1903, Niels Finsen won the Nobel Prize for treating skin tuberculosis with a “chemical ray” lamp (which consisted of light radiation) that he developed, thus introducing phototherapy into modern medicine.

Sunlight has been used as therapy dating back 3500 years to the time of the ancient Egyptians and Indian healers to treat “Leucoderma” also known as vitiligo.


  • Psoriasis
  • Atopic dermatitis Vitiligo
  • Localized scleroderma
  • Cutaneous lymphomas such as mycosis fungoides

In addition to the list beside, daylight photodynamic therapy – where daylight exposure is combined with a chemical being applied to skin -- can also be used as a treatment for early skin cancers.

Diseases that can be treated with heliotherapy are similar to the ones treated with conventional phototherapy in the office.

Psoriasis is a common disease where heliotherapy is a valid treatment option. Psoriasis is an inflammatory skin and systemic disease that can benefit from the anti-inflammatory properties of controlled amounts of UV radiation.
Atopic dermatitis (eczema) is another inflammatory skin disease that can benefit from heliotherapy.


“Disclaimer: It is important to note that when we discuss the benefits of sun exposure, there are very strict guidelines as to the quantity, frequency, and location of the exposure as well as individual factors that determine the recommended sun dose for each person. It is not “free for all”, highlights Dr. Ivan Litvinov, a certified dermatologist at McGill University. For example, being out in the sun on a clear day in the summer between 10:00am-2:00pm is going to be a very high amount exposure and can pose greater health risks, such as developing skin cancer, than going outside during times when the sun is not as strong such as the early morning or late in the afternoon. Similarly, sun exposure in November will be different than sun exposure in June.

Also, only the affected area of skin should be exposed to the sun during the heliotherapy treatment time. The rest of the skin should be protected by clothing or with sunscreen and sunglasses should be worn to protect one’s eyes from the sun. In a setting of daylight photodynamic therapy, a doctor will prescribe a special chemical to the skin before exposing it to the sun for a defined time. “When done carefully and following all dermatologist recommendations heliotherapy can be beneficial, especially in remote and rural locations where a phototherapy booth may not be available nearby”, explains Dr. Litvinov.

Sunlight contains two different kinds of Ultraviolet (UV) radiation, UVA and UVB. In large doses UVA radiation accelerates aging, whereas UVB radiation increases the risk of developing sunburns. Both UVA and UVB rays increase the risk of skin cancer. However, in more controlled doses UV radiation can have beneficial and protective properties, such as antioxidant, anti-inflammatory and immunosuppressive effects on the skin. Sometimes we combine sun and specific chemicals to achieve the desired treatment effect.

In order for the skin to benefit from these effects, sun exposure must surpass a certain threshold which causes some redness in the exposed area in the 24 hours following the treatment. This is not the same as getting sunburned, which must be avoided at all cost. “In fact, burning your skin can make psoriasis and eczemas even worse. Like any treatment – too much of it can quickly lead to problems. Injury by burning the skin can aggravate many inflammatory skin diseases”, says Dr. Litvinov.

Every individual may need to be in the sun for a different amount of time to reach this threshold and exposure time should be discussed with a certified dermatologist on a case-by-case basis. For example, people with lighter skin may need less exposure to achieve the beneficial effect on their skin than people with darker skin tones.

A great advantage of heliotherapy is that sunlight is ubiquitous and is therefore accessible to people of all socioeconomic backgrounds living in rural remote and urban locations. With proper instruction and recommendations from a dermatologist, heliotherapy is a valid alternative to conventional phototherapy for the diseases mentioned above for patients, who may not have conventional phototherapy in their community.

Unfortunately, sunlight is very variable depending on the day, time of day, season and geographic location. Natural sunlight is also a much less controlled source of UV radiation and larger exposures can cause serious harm. In general, office phototherapy is a much more controlled and reliable way to receive this treatment. Please speak to your doctor before pursuing this treatment.

  • Patients with a history of skin cancer
  • Patients with previous exposure to ionizing radiation
  • Patients with very light skin tones
  • Patients with photosensitive connective tissue diseases such as lupus
  • Patients who are taking common photosensitizing medications such as hydrochlorothiazide, certain antibiotics, antifungal treatments and other medications.
  • Patients with Xeroderma pigmentosum
  • Patients with other conditions predisposing them to sun-induced cancers
  • Patients with a history of non-melanoma skin cancer
  • Patients who are immunosuppressed
  • Patients diagnosed with immunoblots diseases.
  • Patients with pemphigus pemphigoid
  • Patients with cataracts
  • Patients with aphakia
  • Patients with a family history of melanoma