Itching (Pruritus): Causes, Symptoms and Treatment

What is Itching?

Itching, medically known as pruritus, is an uncomfortable and often distressing sensation on the skin or in deeper tissue layers that triggers an involuntary urge to scratch. It is one of the most common dermatological complaints and can occur either in a localized form (confined to a specific area) or as generalized itching affecting the entire body. Itching is not a disease in itself, but rather a symptom that can point to a wide variety of underlying conditions.

Causes

The causes of itching are diverse and can be grouped into several categories:

Dermatological Causes

• Atopic Dermatitis (Eczema): A chronic inflammatory skin condition associated with intense itching.
• Psoriasis: Inflammatory skin plaques that frequently cause itching.
• Urticaria (Hives): Allergic wheals accompanied by intense itching.
• Contact Dermatitis: A skin reaction to allergens or irritants.
• Fungal Infections: Such as athlete's foot or ringworm.
• Parasite Infestation: Such as scabies or lice.
• Dry Skin (Xerosis): Particularly common in elderly individuals.

Systemic Causes

• Liver Disease: For example, cholestasis, where bile salts accumulate in the blood and cause itching.
• Kidney Failure: Uremic pruritus caused by the buildup of metabolic waste products.
• Thyroid Disorders: Both overactive and underactive thyroid can lead to itching.
• Diabetes Mellitus: Dry skin and nerve damage may result in itching.
• Blood Disorders: Such as polycythaemia vera or Hodgkin lymphoma.
• Pregnancy: Certain pregnancy-related skin changes are associated with itching.

Neurological and Psychiatric Causes

• Neuropathic Pruritus: Triggered by nerve damage, for example in herpes zoster (shingles).
• Psychogenic Pruritus: Caused by stress, anxiety, or mental health conditions.

Medication-Related Causes

• Certain medications such as opioids, ACE inhibitors, diuretics, or antibiotics can cause itching as a side effect.

Symptoms and Associated Complaints

Itching may be accompanied by additional symptoms that provide clues about the underlying cause:

• Skin redness, wheals, or blisters
• Scaling or thickening of the skin due to chronic scratching (lichenification)
• Sleep disturbances and fatigue from persistent nocturnal itching
• Open wounds or infections from scratching
• Psychological burden, irritability, or depression in chronic cases

Diagnosis

Diagnosis begins with a thorough medical history and physical examination. The physician will ask about the onset, duration, location, and possible triggers of the itching. The following investigations may additionally be performed:

• Blood Tests: Assessment of liver enzymes, kidney function, blood count, thyroid values, and blood glucose.
• Allergy Testing: Prick test or patch test to identify allergens.
• Skin Biopsy: Tissue sampling for microscopic analysis in cases of unclear skin findings.
• Imaging Studies: Ultrasound or further investigations if a systemic condition is suspected.
• Dermatoscopy: Magnified examination of the skin for more detailed assessment.

Treatment

Treatment is primarily directed at the underlying cause. In addition, general measures can be taken to relieve itching:

General Measures

• Moisturizing and emollient skin care products
• Avoidance of known triggers (allergens, irritants, heat)
• Short, lukewarm showers instead of hot baths
• Wearing soft, breathable clothing (e.g., cotton)
• Cooling the affected skin areas with cool, moist compresses

Medical Treatment

• Antihistamines: Block the effects of histamine and relieve allergy-related itching.
• Corticosteroids (topical or systemic): Reduce inflammation in inflammatory skin conditions.
• Calcineurin Inhibitors: Immunomodulating creams (e.g., tacrolimus) for atopic dermatitis.
• Biologics: Modern antibody therapies (e.g., dupilumab) for severe atopic dermatitis.
• Antidepressants or Anticonvulsants: Used for neuropathic or psychogenic pruritus.
• Cholestyramine: For cholestatic itching caused by bile duct obstruction.

Physical Therapies

• Phototherapy (UV Therapy): Particularly effective for chronic pruritus of various causes.
• Balneotherapy (therapeutic baths)

When to See a Doctor

Medical consultation is recommended if itching persists for more than two weeks, occurs without an identifiable cause, significantly disrupts sleep, is accompanied by other symptoms such as weight loss, fever, or jaundice, or if scratching causes open wounds. Chronic or generalized itching should always be medically evaluated, as it may indicate serious underlying conditions.

References

1. Weisshaar E. et al. - European S2k Guideline on Chronic Pruritus. Acta Dermato-Venereologica, 2019. Available at: https://www.medicaljournals.se/acta
2. Ständer S. - Pruritus. New England Journal of Medicine, 2017; 376:348-356. Available at: https://www.nejm.org
3. Yosipovitch G., Bernhard J.D. - Chronic Pruritus. New England Journal of Medicine, 2013; 368:1625-1634. Available at: https://www.nejm.org