What are the other Names for this Condition? (Also known as/Synonyms)

• Chemical-Induced Photoallergic Reaction
• Drug-Induced Photoallergic Reaction
• Photoallergic Medication-Induced Photosensitivity

What is Photoallergic Drug (or Chemical) Induced Photosensitivity? (Definition/Background Information)

• Photosensitivity can be described as an allergic reaction of the body (or skin) on exposure to the sun. This immune reaction may also occur on the usage or consumption of certain medications or chemicals, with subsequent exposure to sunlight (or ultraviolet light). This condition is termed as drug (or chemical) induced photosensitivity
• Drug (or chemical) induced photosensitivity can occur in the following manner:
  • Phototoxic Drug (or Chemical) Induced Photosensitivity, also known as Drug (or Chemical) Induced Phototoxic Reaction
  • Photoallergic Drug (or Chemical) Induced Photosensitivity, also known as Drug (or Chemical) Induced Photoallergic Reaction

Photoallergic Drug (or Chemical) Induced Photosensitivity occurs when an individual has been exposed to and been sensitized to a certain drug/chemical in the past. During this process, the individual’s immune system is ready to launch an immune response when he/she is exposed to the drug/chemical in future, and then further exposed to ultraviolet (UV) light of the sun.

• Thus, an individual does not react to the drug/chemical early when exposed for the first time. However, during subsequent exposure, the body has a more rapid onset of an immune response against the drug/chemical causing associated signs and symptoms
• Photoallergic Drug (or Chemical) Induced Photosensitivity is less common than phototoxic drug (or chemical) induced photosensitivity and generally affects adults
• The drugs/chemicals may be used for treatment or cosmetic purposes, or there may be an occupational exposure, such as while working in agricultural fields or in an industrial plant. The chemical may also be commonly used in the kitchen or toilets (for example as a cleaning fluid)
• The signs and symptoms of Photoallergic Drug (or Chemical) Induced Photosensitivity can be topical (confined to an area in the body) or systemic (widespread in the body). The topical type is more common than the systemic type
• The primary treatment for Photoallergic Drug (or Chemical) Induced Photosensitivity is identifying the offending medication/drug/chemical and its discontinuation. The prognosis of the condition is typically excellent with suitable treatment. However, in severe cases, immunosuppressive therapy can be beneficial

Who gets Photoallergic Drug (or Chemical) Induced Photosensitivity? (Age and Sex Distribution)

• Photoallergic Drug (or Chemical) Induced Photosensitivity is an uncommon condition caused by the body’s sensitization to a chemical/drug/medication (administered for other underlying conditions or due to unintentional exposure) and sun exposure
• Individuals of any age may be at risk for the condition, though this condition is usually seen in adults
• It can affect both males and females
• The condition occurs worldwide; individuals of all racial and ethnic background may be affected

What are the Risk Factors for Photoallergic Drug (or Chemical) Induced Photosensitivity? (Predisposing Factors)

The key risk factor for Photoallergic Drug (or Chemical) Induced Photosensitivity is the administration of certain drugs, or a contact with certain chemicals that can cause the condition as a side effect. The common categories of drugs/chemicals observed to induce this condition include:

• Sunscreens, such as oxybenzone, benzophenone-3, and octocrylene
• Antimicrobial agents such as chlorhexidine and hexachlorophene
• Quinine and quinidine
• Certain fragrances
• NSAIDs such as diclofenac and ketoprofen
• Antibiotics including sulfonamides, quinolones, and griseofulvin
• Chlorpromazine and promethazine - antipsychotics and sedatives

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Photoallergic Drug (or Chemical) Induced Photosensitivity? (Etiology)

Photoallergic Drug (or Chemical) Induced Photosensitivity is considered to be a delayed type hypersensitivity reaction, since the condition occurs on one’s second and subsequent exposure to ultraviolet light.

• The drugs/medications (including topical creams or lotions) have been previously taken or applied for various conditions, or a past exposure of the body to certain chemicals has occurred from an industrial or agricultural source
• The body gets sensitized to the drug or chemical and its response to ultraviolet light or sunlight. There is no adverse reaction of the body to the drug or chemical when exposure occurs for the first time
• Subsequent to this and after a certain time period, the body prepares itself to launch an immune response for a future drug/chemical exposure, which is followed by an UV light exposure (either from the sun or from other sources). Thus, it may be stated that the skin has been ‘primed’ for an allergic reaction
• The offending drug/chemical potentially causes an abnormal cell-mediated immune response in the body resulting in the associated signs and symptoms of the condition

What are the Signs and Symptoms of Photoallergic Drug (or Chemical) Induced Photosensitivity?

The signs and symptoms of Photoallergic Drug (or Chemical) Induced Photosensitivity can be local or systemic.

• Local or topical condition: The signs and symptoms are mostly confined to the area of exposure. This is the most common type of Drug (or Chemical) Induced Photoallergic Reaction
• Systemic condition: Not only the skin, but other parts of the body may also be affected; this type of reaction is not frequently observed

The signs and symptoms may include:

• Itching all over the body, which is a very prominent sign
• General body aches
• Fever
• Redness of skin
• Blister formation (vesicles and bullae)
• The condition is usually confined to the exposed areas, but can occur in non-exposed areas too

The severity of Drug (or Chemical) Induced Photoallergic Reaction may vary; it is difficult to predict who will get mild or severe symptoms.

How is Photoallergic Drug (or Chemical) Induced Photosensitivity Diagnosed?

In many cases, for some unknown reasons, the upper eyelids, the region under the nose (philtrum), and the chin are spared of any symptoms. This factor can additionally help in the diagnosis of Photoallergic Drug (or Chemical) Induced Photosensitivity.

The following are the diagnostic methods and tests that may be used:

• A complete physical examination and a thorough medical and occupational history (which includes the use of any drugs, nature of occupation, etc.) are very important
• Dermoscopy: Dermoscopy is a diagnostic tool where a dermatologist examines the skin using a special magnified lens
• Photopatch test: It is an allergic (skin) patch test combined with exposure to ultraviolet radiation
• Skin or tissue biopsy: A skin or tissue biopsy is performed and sent to a laboratory for a pathological examination, who examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. A biopsy is performed to rule out other similar conditions

Note: In most cases, based on the signs and symptoms, a diagnosis can be made by the dermatologist through a physical examination and medical history study, without resorting to a biopsy. However, determining if the skin response is a purely allergic reaction, or requires the additional factor of light exposure can be difficult and require photopatch testing by a specialist dermatologist.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Photoallergic Drug (or Chemical) Induced Photosensitivity?

The complications of Photoallergic Drug (or Chemical) Induced Photosensitivity may include:

• Secondary bacterial and fungal infections: The condition may cause continuous itching and scaling of the skin, which creates skin moistness, thereby providing a suitable environment for bacteria and fungi to grow and thrive
• The skin heals with increased or decreased pigmentation
• The lesions can last for several months and years, called Persistent Drug (or Chemical) Induced Photoallergic Reaction, resulting in self-image issues, emotional stress, and psychological trauma (depression) in some individuals

How is Photoallergic Drug (or Chemical) Induced Photosensitivity Treated?

The treatment of Photoallergic Drug (or Chemical) Induced Photosensitivity may include:

• Discontinuing the drug/medication (even topical ointment or cream) responsible for the effect may result in a cure
• In case the condition is due to an industrial or agriculture exposure to a certain chemical, then suitable protective measures may be taken to avoid coming into contact with the offending chemical
• Topical treatments includes cooling the skin using moist towels and application of moisturizing creams to soothe the condition
  • Use of topical ointments, lotions, and creams - these may be antiseptic and anti-inflammatory applications
  • Topical steroidal creams can help reduce inflammation
• Systemic treatment may be required in some cases
  • It may include medications, such as aspirin and other non-steroidal anti-inflammatory over-the-counter painkillers
  • In severe cases, oral steroids and IV fluids may be necessary
• In severe cases of Drug (or Chemical) Induced Photoallergic Reaction, immunosuppressive therapy can be helpful
• Providing reassurance and helping with feelings of stress and anxiety
• Follow-up care with regular screening and checkups are important, since the condition may last for many months and years

A few self-care tips and home remedies that may prevent aggravation of the condition may include:

• Completely avoid scratching the affected areas; keep nails trimmed
• A comfortable, cool bath may help soothe the skin; but, avoid excessive washing and scrubbing of the skin
• Wear smooth cotton clothes
• Use only mild perfumes, soaps, and detergents
• Drinking lots of water or fluids

How can Photoallergic Drug (or Chemical) Induced Photosensitivity be Prevented?

Currently, it is not possible to prevent Photoallergic Drug (or Chemical) Induced Photosensitivity.

• Stopping the medication causing the condition as early as possible is important. The healthcare provider may prescribe alternative medications to treat the existing/underlying condition
• If the allergic reaction is following an exposure to industrial compounds or chemicals, then suitable protective or safety gear may be used to prevent any further contact with the chemical
• Periodic monitoring or follow-up of the condition with the healthcare provider is recommended

What is the Prognosis of Photoallergic Drug (or Chemical) Induced Photosensitivity? (Outcomes/Resolutions)

• The prognosis of Photoallergic Drug (or Chemical) Induced Photosensitivity is usually excellent with appropriate treatment
• In general, it is easier to treat topical or localized reactions than systemic or widespread conditions

Additional and Relevant Useful Information for Photoallergic Drug (or Chemical) Induced Photosensitivity:

Cleaning the skin too hard with strong chemicals or soaps may aggravate the skin condition. Care must be taken avoid strong soaps and chemicals that can potentially worsen the condition.