Pruritus can be caused by a wide range of factors, often classified into dermatological, systemic, neurological, and psychogenic causes:

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Dermatological Causes:

• Eczema (Atopic Dermatitis): A common cause of chronic itching, particularly in children, characterized by red, inflamed, and itchy skin.

• Psoriasis: A condition where rapid skin cell turnover leads to scaling and itching.

• Contact Dermatitis: Caused by skin contact with an irritant or allergen, leading to inflammation and itching.

• Urticaria (Hives): Itchy, raised welts on the skin, often caused by an allergic reaction.

• Lichen Planus: An inflammatory condition that causes itchy, flat-topped purple bumps on the skin.

• Scabies: A contagious skin infestation by the mite Sarcoptes scabiei, causing intense itching, especially at night.

• Insect Bites and Stings: Mosquito bites, bedbug bites, or stings from bees and wasps often cause localized itching.

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Systemic Causes:

• Chronic Kidney Disease: Itching is a common symptom in advanced kidney disease due to the buildup of waste products in the blood.

• Liver Disease: Conditions such as cholestasis can lead to the accumulation of bile salts in the skin, causing itching.

• Thyroid Disease: Both hyperthyroidism and hypothyroidism can be associated with pruritus.

• Iron Deficiency Anemia: Itching can occur in iron-deficient states, particularly in the absence of other skin conditions.

• HIV/AIDS: Pruritus is a common symptom in individuals with HIV, often due to opportunistic infections or the virus itself.

• Diabetes: Poorly controlled diabetes can lead to dry skin and pruritus, particularly in the lower extremities.

 

Neurological Causes:

• Neuropathic Itch: Conditions like multiple sclerosis, shingles, or diabetic neuropathy can cause itching due to nerve damage.

• Postherpetic Neuralgia: Persistent itching or pain following shingles can occur in the affected nerve distribution.

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Psychogenic Causes:

• Psychiatric Disorders: Conditions such as depression, anxiety, or obsessive-compulsive disorder (OCD) can manifest as pruritus.

• Delusional Parasitosis: A rare psychiatric condition where individuals believe they are infested with parasites, leading to severe itching and scratching.

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Drug-Induced Pruritus:

• Medications: Certain medications, including opioids, antibiotics, and antimalarials, can cause itching as a side effect. Withdrawal from substances like opioids can also lead to pruritus.

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Environmental Factors:

• Dry Skin (Xerosis): Particularly in elderly individuals, dry skin is a common cause of itching, especially during winter when humidity levels are low.

• Exposure to Irritants: Soaps, detergents, and other chemicals can irritate the skin, leading to pruritus.

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