Phototoxicity: Difference between revisions

Revision as of 06:46, 16 February 2025

Phototoxicity

Phototoxicity is a chemically induced skin irritation that requires light exposure to activate the chemical agent. This condition is often confused with photoallergy, but unlike photoallergy, phototoxicity does not involve the immune system. Instead, it is a non-immunologic response that occurs when a phototoxic agent absorbs ultraviolet (UV) light and releases energy that damages surrounding tissues.

Mechanism of Action

Phototoxic reactions occur when a phototoxic substance absorbs ultraviolet radiation and becomes excited to a higher energy state. This energy is then transferred to surrounding molecules, leading to the formation of reactive oxygen species (ROS) and free radicals. These reactive species can cause direct damage to cellular membranes, proteins, and DNA, resulting in inflammation and cell death.

Common Phototoxic Agents

Phototoxicity can be triggered by a variety of substances, including certain medications, cosmetics, and plants. Some well-known phototoxic agents include:

Psoralens - Found in plants like Rue officinale and used in PUVA therapy for psoriasis.
Tetracyclines - A class of antibiotics that can cause phototoxic reactions when patients are exposed to sunlight.
Fluoroquinolones - Another class of antibiotics known for their potential to cause phototoxicity.
Coal tar - Used in the treatment of skin disorders, it can cause phototoxic reactions when exposed to UV light.

Symptoms

The symptoms of phototoxicity are similar to those of a severe sunburn and can include:

Redness and inflammation of the skin
Blistering
Pain and tenderness
Swelling

These symptoms typically appear within minutes to hours after exposure to the phototoxic agent and sunlight.

Prevention and Management

Preventing phototoxicity involves avoiding exposure to known phototoxic agents and minimizing sun exposure, especially during peak UV radiation hours. Protective clothing and broad-spectrum sunscreen can also help reduce the risk of phototoxic reactions.

Management of phototoxicity focuses on symptomatic relief and may include:

Cool compresses to soothe the skin
Topical corticosteroids to reduce inflammation
Analgesics for pain relief

Related Pages

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-'''Phototoxicity''' is a chemically induced skin irritation, requiring light, that does not involve the immune system. It is a type of [[photosensitivity]]. The skin response resembles an exaggerated sunburn. The involved chemical may enter into the skin by topical administration or it may reach the skin via systemic circulation following ingestion or parenteral administration. The chemical needs to be "photoactivated" by light in the UVA spectrum. The mechanism of action varies — the chemical may become excited by light and directly damage surrounding tissue, or it may lead to the formation of [[free radicals]] that damage tissue indirectly.
+{{DISPLAYTITLE:Phototoxicity}}
-== Causes ==
+== Phototoxicity ==
-Phototoxicity can be caused by various agents:
-* Certain [[medications]], such as [[tetracycline]], [[sulphonamides]], [[quinolones]], [[phenothiazines]], and [[psoralens]]
+[[File:Effet_de_la_rue_officinale.jpg|thumb|right|Phototoxic reaction on skin after exposure to Rue officinale.]]
-* Certain [[essential oils]], such as [[bergamot]], [[lime]], [[lemon]], [[grapefruit]], [[cedar]], and [[fig]]
-* Certain [[plants]], such as [[giant hogweed]], [[wild parsnip]], [[lemon verbena]], and [[St John's wort]]
+'''Phototoxicity''' is a chemically induced skin irritation that requires light exposure to activate the chemical agent. This condition is often confused with [[photoallergy]], but unlike photoallergy, phototoxicity does not involve the immune system. Instead, it is a non-immunologic response that occurs when a phototoxic agent absorbs ultraviolet (UV) light and releases energy that damages surrounding tissues.
-* Certain [[chemicals]], such as [[furocoumarins]], [[coumarins]], and [[xanthotoxin]]
+== Mechanism of Action ==
+Phototoxic reactions occur when a phototoxic substance absorbs [[ultraviolet radiation]] and becomes excited to a higher energy state. This energy is then transferred to surrounding molecules, leading to the formation of reactive oxygen species (ROS) and free radicals. These reactive species can cause direct damage to [[cellular membranes]], [[proteins]], and [[DNA]], resulting in inflammation and cell death.
+== Common Phototoxic Agents ==
+Phototoxicity can be triggered by a variety of substances, including certain [[medications]], [[cosmetics]], and [[plants]]. Some well-known phototoxic agents include:
+* [[Psoralens]] - Found in plants like [[Rue officinale]] and used in [[PUVA therapy]] for [[psoriasis]].
+* [[Tetracyclines]] - A class of antibiotics that can cause phototoxic reactions when patients are exposed to sunlight.
+* [[Fluoroquinolones]] - Another class of antibiotics known for their potential to cause phototoxicity.
+* [[Coal tar]] - Used in the treatment of skin disorders, it can cause phototoxic reactions when exposed to UV light.
 == Symptoms ==
-Symptoms of phototoxicity can include:
-* Redness (similar to sunburn)
+The symptoms of phototoxicity are similar to those of a severe [[sunburn]] and can include:
+* Redness and inflammation of the skin
+* Blistering
+* Pain and tenderness
 * Swelling
-* Itching
-* Burning
-* Blisters and scaling
-* Hyperpigmentation (dark patches on the skin)
-== Treatment ==
+These symptoms typically appear within minutes to hours after exposure to the phototoxic agent and sunlight.
-Treatment for phototoxicity is similar to the treatment for a severe sunburn. This can include:
-* Cold compresses
+== Prevention and Management ==
-* Over-the-counter hydrocortisone creams
-* Non-prescription pain relievers
+Preventing phototoxicity involves avoiding exposure to known phototoxic agents and minimizing sun exposure, especially during peak UV radiation hours. Protective clothing and broad-spectrum [[sunscreen]] can also help reduce the risk of phototoxic reactions.
-* Stay out of the sun as much as possible until the skin has healed
+Management of phototoxicity focuses on symptomatic relief and may include:
+* Cool compresses to soothe the skin
+* Topical [[corticosteroids]] to reduce inflammation
+* [[Analgesics]] for pain relief
-== Prevention ==
+== Related Pages ==
-Prevention of phototoxicity involves avoiding known triggers, such as certain medications, plants, and chemicals. If exposure cannot be avoided, protective clothing and sunscreens may help prevent a reaction.
-== See also ==
-* [[Phototoxicity (eye)]]
 * [[Photoallergy]]
-* [[Photosensitivity in humans]]
+* [[Sunburn]]
-* [[Drug-induced photosensitivity]]
+* [[Psoriasis]]
-* [[Photodermatitis]]
+* [[PUVA therapy]]
-[[Category:Skin conditions]]
+[[Category:Dermatology]]
-[[Category:Photosensitivity reactions]]
+[[Category:Photobiology]]
-[[Category:Toxic effects of substances chiefly nonmedicinal as to source]]
-{{stub}}