Skin Itching: All About Causes and Innovative Treatment Approaches

Skin Itching: What Is It and Why Does It Occur?

Itching (pruritus) is an unpleasant sensation that triggers the urge to scratch. It is a primary symptom of many dermatological and systemic conditions [3]. Skin itching can significantly impair quality of life, affecting sleep, mood, and daily activities [2]. The causes of itching are diverse and can be associated with both direct skin problems and dysfunctions of internal organs.

Main Dermatological Causes of Itching

Many skin diseases manifest with intense itching. Among the most common are:

• Atopic Dermatitis (AD): This is a chronic inflammatory skin disease characterized by severe itching and eczematous rashes that significantly reduce quality of life [2, 5, 6]. AD occurs in people of all ages, sexes, and ethnic groups [1].
• Psoriasis: A chronic non-communicable disease, also frequently accompanied by itching [3, 5].
• Contact Dermatitis: Skin inflammation caused by contact with an irritant or allergen, manifesting as itching and redness [3].
• Urticaria: Characterized by the appearance of itchy wheals on the skin [3].
• Lichen Simplex Chronicus (Neurodermatitis): Skin thickening caused by constant scratching due to itching [3].
• Mycosis Fungoides: A rare malignant skin disease that can cause itching [3].
• Scars: Some scars can cause itching [3].
• Hand Eczema: A chronic condition affecting about 14.5% of the population, significantly worsening quality of life and leading to missed work or school [8].
• Cutaneous Adverse Drug Reactions: These are among the most common non-infectious rashes in children. They can manifest as morbilliform, urticarial, bullous, pustular, or psoriasiform eruptions [5].

Systemic Diseases and Other Factors Causing Itching

Itching can be a sign of more serious health issues not directly related to the skin:

• Autoimmune Diseases: For example, systemic lupus erythematosus can manifest with skin signs such as malar rash, discoid lupus, and photosensitivity [3, 5].
• Kidney or Liver Diseases: Frequently accompanied by generalized pruritus [3].
• Kawasaki Disease: May cause changes in the lips, mouth, extremities, as well as a polymorphous rash [5].
• Type 1 Diabetes Mellitus: Characterized by dry skin (xerosis) and skin changes on the face, hands, and feet [5].
• Genetic Conditions: Some genetic disorders manifest with skin pigmentation changes [5].
• Infections: In children, infections are a frequent cause of erythroderma (generalized redness and peeling of the skin) [4].

Modern Approaches to Diagnosing Itching

For effective treatment of itching, it is crucial to accurately determine its cause [3]. Diagnosis begins with a thorough medical history and clinical examination. The physician may use specialized tools to assess the condition:

• SCORAD Index (SCORing Atopic Dermatitis Index): Used to quantitatively assess the severity of atopic dermatitis and the intensity of itching [2].
• Dermatology Life Quality Index (DLQI): Helps assess the impact of a skin disease on a patient's quality of life [2].
• Atopic Dermatitis Control Tool: Used to assess long-term control over the disease [2].

Depending on the suspected cause, additional studies may be prescribed, such as blood tests, skin biopsy, or allergy tests.

Effective Itching Treatment: From Basic Remedies to Innovations

The approach to treating itching depends on its underlying cause. Although antihistamines are often considered first-line therapy, their role is actually limited to urticaria and drug-induced reactions [3]. The pathophysiological mechanisms of various conditions causing itching differ, requiring an individualized approach [3].

Treatment of Atopic Dermatitis (AD):

• First line: Includes skin care measures (e.g., use of emollients), topical corticosteroids, and calcineurin inhibitors [1, 5].
• Second line: If local remedies are ineffective, phototherapy may be prescribed [1, 6]. Ultraviolet A1 (UVA1) radiation is effective for acute AD, and narrow-band ultraviolet B (NB-UVB) for chronic AD [1]. In severe cases, phototherapy can be combined with systemic drugs such as corticosteroids [1]. Currently, there are no uniform guidelines for using phototherapy in AD, but it is recognized as an effective method [1, 6].
• New topical and systemic drugs: For moderate to severe AD, new topical agents such as Janus kinase inhibitors (JAK inhibitors) or phosphodiesterase-4 inhibitors (PDE4 inhibitors) are used [2]. Advanced systemic treatments are available for severe and/or refractory forms of AD. For example, abrocitinib (an oral JAK inhibitor) showed a significant reduction in symptoms and itching, and outperformed dupilumab in some parameters as early as the second week of treatment [7]. Dupilumab (subcutaneous injections) is also an effective option [7].

In recent years, new drugs with attractive efficacy and safety profiles have emerged, opening new possibilities for more ambitious goals in treating patients with itching [3].

Features of Itching in Children and Localized Forms

Itching in children:

• Atopic dermatitis: Is one of the most common inflammatory skin diseases in children [1, 5].
• Erythroderma: Although this condition is well studied in adults, there is less research in children. In children, erythroderma poses a major challenge due to its potentially life-threatening nature. Causes may include infections (40%), ichthyosiform erythroderma (25%), atopic dermatitis (15%), infantile seborrheic dermatitis (10%), as well as drug reactions (29%), genodermatoses, psoriasis, and staphylococcal scalded skin syndrome (18% each) [4]. Treatment of erythroderma in children is mainly supportive, with correction of hematological, biochemical, and metabolic abnormalities when necessary [4].
• Drug reactions: Among non-infectious rashes in children, cutaneous adverse drug reactions are very common [5].
• Therapy: For children with AD, emollients and topical corticosteroids are the first line. Topical calcineurin inhibitors are used as a second line allowing steroid-sparing, especially for sensitive areas such as the face and eyelids [5].

Hand Eczema:

This is a chronic condition that can be very debilitating. Standard treatment includes moisturizing creams, topical steroids, and in more severe cases, systemic medications. Thanks to new therapeutic targets and advancements, it is now possible to manage hand eczema more effectively by targeting its core mechanisms [8].

Sources

• 1. Safety and efficacy of phototherapy in the treatment of eczema. (Advances in experimental medicine and biology, 2017) https://pubmed.ncbi.nlm.nih.gov/29124712/
• 2. Expert consensus on the management of moderate-to-severe atopic dermatitis in Qatar. (The Journal of dermatological treatment, 2023) https://pubmed.ncbi.nlm.nih.gov/37700510/
• 3. Pruritus in dermatology: Part 2 - Diseases and treatment. (Actas dermo-sifiliograficas, 2023) https://pubmed.ncbi.nlm.nih.gov/37302478/
• 4. Erythroderma in children. (Indian journal of dermatology, venereology and leprology, 2010) https://pubmed.ncbi.nlm.nih.gov/20657113/
• 5. Common skin conditions in children: non-infectious eruptions. (FP essentials, 2017) https://pubmed.ncbi.nlm.nih.gov/28196317/
• 6. Phototherapy for atopic eczema. (The Cochrane database of systematic reviews, 2021) https://pubmed.ncbi.nlm.nih.gov/34709669/
• 7. Efficacy and safety of abrocitinib in patients with severe and/or refractory atopic dermatitis: post-hoc analysis of the phase 3 randomized JADE COMPARE study. (American journal of clinical dermatology, 2023) https://pubmed.ncbi.nlm.nih.gov/37213005/
• 8. Review of current and emerging treatments for hand eczema. (Journal of cutaneous medicine and surgery, 2023) https://pubmed.ncbi.nlm.nih.gov/37496489/

Disclaimer: The information provided in this article is for reference purposes only and should not be used for self-diagnosis or self-treatment. Always consult a qualified physician for diagnosis and prescription of adequate treatment.