Know All About Photosensitivity

What Is Photosensitivity?

Photosensitivity is the sensitivity to sunlight where the skin reacts to sunlight alone or sunlight and chemicals. The chemicals causing this photosensitivity are found in fragrance-giving perfumes, makeup products, lotions, creams, foods, or medicines. Photosensitivity induced by exogenous agents can be divided into,

• Phototoxicity.

• Photoallergy.

Phototoxicity:

Phototoxicity is the result of direct tissue and cellular injury caused by phototoxic agents and radiation. It can occur in all individuals, provided the dose of the agent, and inducing wavelengths are adequate.

Photoallergy:

In contrast, photoallergy is a delayed-type hypersensitivity response to a molecule that turns antigenic on the absorption of photons. It has a sensitization phase, an incubation period of 7 to 10 days following the first exposure. Thus, it occurs only in previously sensitized individuals and requires only minimal concentration of the photoallergy. Though several medications have been reported to cause photosensitivity, the exact prevalence of the same in the general population is unknown.

What Are the Photoallergic and Phototoxic Agents?

Photoallergens -

a) Systemic Photo Allergens:

Drugs such as,

1. Griseofulvin.

2. Quinine.

3. Quinolone.

4. Enoxacin.

5. Quinidine.

6. Ketoprofen.

7. Piroxicam.

8. Pyridoxine.

b) Topical Photo Allergens:

Sunscreen ingredients including,

1. Benzophenones.

2. PABA (para-aminobenzoic acid).

3. Avobenzone.

Fragrances such as,

1. 6-Methyl Coumarin.

2. Musk ambrette.

3. Sandalwood oil.

Phototoxic Agents -

a) Systemic Phototoxic Agents:

Systemic phototoxic agents include,

1. Voriconazole.

2. Griseofulvin.

3. Chloroquine.

4. Quinine.

5. Sulfonamide.

6. Tetracyclines.

7. Quinolone.

8. Furosemide.

9. Thiazide.

10. Azathioprine.

11. Methotrexate.

12. Alprazolam.

13. Phenothiazine, etc.

b) Topical Phototoxic Agents:

Topical phototoxic agents include,

1. Fluorescein dye.

2. Fluorouracil.

3. Furocoumarins.

4. Retinoids.

5. Rose bengal.

6. Tar.

How Does Photosensitivity Occur?

Photosensitivity occurs from an unusual reaction to,

• The electromagnetic spectrum of sunlight.

• Chromophore within the skin.

The Electromagnetic Spectrum of Sunlight:

It ranges from cosmic rays, ultraviolet rays, infrared, microwaves, and radio waves through visible light. The ultraviolet rays are of three types,

• UVA rays (320–400 nm) - Cause tanning and inhibits immune reactions in the skin.

• UVB rays (290–320 nm) - Cause tanning and sunburn.

• UVC rays (200–290 nm) - Do not cause any side effects as they do not reach the earth’s surface.

What Are the Symptoms of Photosensitivity?

People start to experience the signs and symptoms, usually within 3 hours of sun exposure. Also, they typically disappear within a day after sun exposure and can also last for a week or more. The following are the symptoms that the patient experience,

• Itchiness.

• Rashes.

• Hives.

• Blisters.

In addition, the signs and symptoms increase in conditions like,

• Fair skin.

• Working outside.

• Birth control pills.

• Light-colored hair.

• Family history of photosensitivity.

• Blue eyes.

• Antibiotic medicines.

• Autoimmune diseases.

• Diuretics or anti-inflammatories.

What Are the Clinical Features of Photosensitivity?

Phototoxicity:

Acute phototoxicity develops within hours following exposure to a topical or systemic phototoxic agent and appropriate UVR (ultraviolet radiation). Erythema, edema as well as burning and stinging sensationcharacterize the initial presentation with vesicles and bullae seen in severely affected patients.

Photoallergy:

Pruritic eczematous eruptions are seen in photo distributed areas in a sensitized individual within 24 to 48 hours after exposure to the photo allergens and sunlight. Vesicles and bullae may develop in severe photoallergy.

Patient Evaluation:

• Most important is the history of exposure to known photosensitizers.

• Whether window glass filtered sunlight (UVB is filtered out by window glass) can induce cutaneous eruption is to be ascertained as the action spectrum for phototoxicity is usually within the UVA range.

• The distribution of the cutaneous eruption is a useful clue to the type of responsible photosensitizer. Widespread eruptions are suggestive of phototoxicity induced by systemic photosensitizers, and localized eruptions are suggestive of photoallergic contact dermatitis induced by topical photosensitizers.

• A burning sensation accompanies vesicular and bullous eruptions, most commonly associated with phototoxicities.

• Eczematous eruptions strongly suggest photoallergy and pruritus is a usual feature.

How Is Photosensitivity Diagnosed?

Tell the doctor about the signs and symptoms and get your skin examined. Also, inform the doctor about the medicines you are taking and the creams, perfume, or lotions used. The things used to diagnose photosensitivity are,

• Photo testing.

• Photo patch.

These testing devices are done in small areas of the skin that are exposed to artificial light. They help the doctor identify whether the symptoms were caused by light and a chemical or light alone.

Also, skin biopsies are needed to test for any particular medical conditions causing the symptoms.

How Is Photosensitivity Treated?

Avoidance of photo allergens and phototoxic agents is the mainstay of treatment. For already erupted lesions, one should get evaluated, and depending on the severity, it can be treated with,

Steroids - Topical or systemic steroids for a shorter duration may help to decrease itching and inflammation. Steroids can be in the form of an injection, cream, or pill.

NSAIDs (nonsteroidal anti-inflammatory drugs)- Ibuprofen decreases the pain, fever, and swelling. They are available with or without a doctor's prescription. NSAIDs can cause kidney problems and stomach bleeding in certain people and when taken with a blood thinner, ask the doctor whether NSAIDs are safe to take along with blood thinners. Also, read the medicine label always before usage and follow the directions. Avoid giving these medicines to children under 6 months of age without a doctor's advice.

Antihistamines - It helps to decrease itching.

Phototherapy - In this treatment, the skin is exposed to doses of ultraviolet light slowly, and it helps the skin adjust to the sunlight.

How to Prevent and Manage the Symptoms of Photosensitivity?

• Apply a cool, damp cloth on the rash or spray cool water to that area.

• Protect the skin by wearing broad-spectrum sunscreens, at least with an SPF of 30, also on cool and cloudy days. The most important thing to know about sunscreen is to apply it every 2 hours.

• Protect the skin by avoiding direct sunlight from 10 AM to 3 PM. Choose shady areas to spend time.

• Avoid using tanning beds.

• Avoid using plants, fruits, and vegetables that cause photosensitivity when they contact the skin.

The temporary discoloration is caused by the following, that is darkening of the skin when the skin is in contact with the sunlight, such as,

1. Mango peel.

2. Lime juice.

3. Parsnips.

The most common phototoxic fruits and vegetables are,

1. Parsley.

2. Lime.

3. Celery.

4. Carrots.

5. Mango peel.

6. Figs.

7. Parsnips.

• Protect the skin by wearing full sleeves and pants or long skirts when in the sun.

• Protect the skin by wearing a hat with a wide brim to shade the face, neck, and ears.

• Wear sunglasses.