Know All About Photosensitivity

What Is Photosensitivity?

Photosensitivity is the sensitivity to sunlight where the skin reacts to sunlight alone or sunlight and chemicals. Photosensitization is the term used to describe the increased vulnerability of skin to UV light-induced damage. The chemicals causing this photosensitivity are found in fragrance-giving perfumes, makeup products, lotions, creams, foods, and medicines.

Photosensitivity induced by exogenous agents can be divided into,

• Phototoxicity.

• Photoallergy.

Phototoxicity:

Phototoxicity results from direct tissue and cellular injury caused by phototoxic agents and radiation. It can occur in all individuals, provided the dose of the agent and the 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, incubating for 7 to 10 days following the first exposure. Thus, it occurs only in previously sensitized individuals and requires only a minimal concentration of the photoallergy. Though several medications have been reported to cause photosensitivity, the exact prevalence in the general population is unknown.

What Happens If Melanin Decreases?

Melanin is a natural pigment in the body that produces the color of an individual's eyes, skin, and hair. In the body, normally more melanins are present. In some people, it is produced more, and they have darker skin, hair, and eyes due to more melanin in their bodies. Some people have lighter skin, eyes, and hair, produced by less melanin. The color pigment of melanin is produced by the special cells called melanocytes.

A low level of melanin leads to some complications, like

• Vitiligo - The melanocytes in the skin are destroyed by the immune system and cause white patches on the skin. Skin appears to have a pale and chalky appearance.

• Melasma - Melasma is a skin disease characterized by brown or red patches on the skin, arm, chin, or face. It may feel.

• Albinism - It is a rare disease that gives people very lighter skin, hair, and color, due to a very low melanin in the body compared to normal. It may lead to vision problems.

What Are the Photoallergic and Phototoxic Agents?

Photoallergens -

a) Systemic Photo Allergens:

Drugs such as,

• Griseofulvin.

• Quinine.

• Quinolone.

• Enoxacin.

• Quinidine.

• Ketoprofen.

• Piroxicam.

• Pyridoxine.

b) Topical Photo Allergens:

Sunscreen ingredients including,

• Benzophenones.

• PABA (para-aminobenzoic acid).

• Avobenzone.

• Fragrances such as,

• 6-Methyl Coumarin.

• Musk ambrette.

• Sandalwood oil.

Phototoxic Agents -

a) Systemic Phototoxic Agents:

Systemic phototoxic agents include,

• Voriconazole.

• Griseofulvin.

• Chloroquine.

• Quinine.

• Sulfonamide.

• Tetracyclines.

• Quinolone.

• Furosemide.

• Thiazide.

• Azathioprine.

• Methotrexate.

• Alprazolam.

• Phenothiazine, etc.

b) Topical Phototoxic Agents:

Topical phototoxic agents include,

• Fluorescein dye.

• Fluorouracil.

• Furocoumarins.

• Retinoids.

• Rose bengal.

• 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 inhibit 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 within 3 hours of sun exposure. Also, they typically disappear within a day after sun exposure and can 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, and burning and stinging sensation characterize 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 suggest phototoxicity induced by systemic photosensitizers, and localized eruptions suggest 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 the individual's skin examined. Also, inform the doctor about the medicines, 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, 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 photoallergens 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 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 before use and follow the directions. Avoid giving these medicines to children under 6 months 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 to the rash or spray cool water.

• Protect the skin by wearing broad-spectrum sunscreens, at least with an SPF of 30, 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 sunlight, such as,

• Mango peel.

• Lime juice.

• Parsnips.

The most common phototoxic fruits and vegetables are,

• Parsley.

• Lime.

• Celery.

• Carrots.

• Mango peel.

• Figs.

• Parsnips.

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

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

• Wear sunglasses.

Conclusion

Many foods, such as figs, parsley, lime, dill, and fennel, might increase the skin's susceptibility to the sun's harmful rays. Those who are sensitive to light should stay away from these foods. Chemicals and drugs may react with UV light to cause photosensitivity. Use home remedies and natural sunscreen to reduce photosensitivity.