Sensitivity to UV Light

For some people with photosensitivity, the sun can seem like an enemy.

People generally are light-loving creatures who are active when the sun is shining outside. However, some individuals are sensitive to certain types of light that contain ultraviolet rays. Although this condition usually isn't serious, it can be debilitating in severe cases and almost always gives the sufferer at least mild discomfort. Since sensitivity to ultraviolet rays may mimic other skin conditions, it is beneficial to know more about the problem before seeking a final diagnosis.

Definition

Sensitivity to ultraviolet light, also known as photosensitivity, is an intolerance for light within the ultraviolet spectrum, which is light people cannot see. It results in irritation of the skin. Some people refer to photosensitivity as sun allergy, but the sun is not the only agent involved in photosensitivity and not all photosensitivity involves allergic response. The condition usually shows up with exposure to the sun, but it also can appear after exposure to any lamp that emits UV rays.

Types

There are five primary types of photosensitivity, according to Dermnetnz.org. These include idiopathic, exogenous, metabolic, photoexacerbated and genetic photosensitivity. All of these types have different causes.

Causes

Dermnetnz.org explains that doctors do not know what causes idiopathic photosensitivity in most cases. Exogenous photosensitivity occurs when a person puts an external agent, such as a topical cream or medicine, on the skin; the sunlight either activates the agent so it directly damages the skin (phototoxic reaction) or it changes the drug so the body's immune system wants to attack it (photoallergic reaction). Metabolic photosensitivity occurs when there is a problem with a person's metabolic function or chemical levels. Photoexacerbated photosensitivity is caused by underlying medical conditions that may affect the skin such as lupus. Genetic photosensitivity is the result of genetic defect.

Ultraviolet Types

People may be sensitive to any one of the three major types of ultraviolet light. These include ultraviolet A, ultraviolet B, and ultraviolet C. According to Dermnetnz.org, most people are sensitive to ultraviolet A.

Symptoms

People with photosensitivity may experience itching, burning, redness or blistering of the skin. Some individuals experience a rash known as photodermatosis.

Testing

Doctors test people for photosensitivity by exposing an area of skin to a light source that emits ultraviolet rays. If the skin reacts to the light, then a diagnosis of photosensitivity is given. If a doctor suspects that the photosensitivity is exogenous, that is, arising from contact with a substance, then the doctor may apply a patch containing a suspected substance to the skin for 1 to 2 days and then perform the light test. If the skin reacts primarily where the patches were placed, then this indicates the substance is problematic.

Treatment

According to Dermnetnz.org and Medicinenet.com, doctors typically treat photosensitivity by using sunscreen and limiting sun exposure. Topical ointments and oral tablets also relieve symptoms. In some cases, people have to cease using agents that seem to increase photosensitivity. These methods may not "cure" the photosensitivity, depending on the cause.

References

• Medicinenet: Sun-Sensitive Drugs (Photosensitivity)
• Dermnetnz: Photosensitivity (Sun Allergy)