Written by Dermatologists for Pharmacists.

		Skin Pharmacies
		Free Subscription
		About Us
		Dermatology Glossary and Images
		Skin Care Network
Skin Pharmacies INDEX
		

The Management of Itchy Skin

R. Vender, MD, FRCPC
Division of Dermatology McMaster University, and
Director of Dermatrials Research, Hamilton, Canada

Introduction

Itchy skin is a very common complaint seen in family practice as well as in dermatology practice. Causes of itchiness are extremely diverse and wide spread. A subset of nociceptive C neurons is responsible for the transmission of itch or pruritus, and these mediators (mainly histamine) can act centrally or peripherally. Skin disease that can mediate itchiness can originate in the skin or even in the central or peripheral nervous systems.

Dermatologic Diseases With Pruritus

Dermatologic Disease	Cause
Infestation	Scabies Pediculosis Arthropod bites Schistosomal cercarial dermatitis (swimmer’s itch)
Inflammation	Atopic dermatitis Stasis dermatitis Irritant or allergic contact dermatitis Lichen simplex chronicus Urticaria Psoriasis, parapsoriasis Prurigo nodularis Drug hypersensitivity Mastocytosis Bullous disease, e.g., dermatitis herpetiformis, bullous pemphigoid Pityriasis rubra pilaris Polymorphous light eruption Eosinophilic pustular folliculitis (Ofuji’s disease) Prurigo pigmentosa PUPPP (pruritic urticaria papules and plaques of pregnancy)
Infections	Fungal infections, e.g., inflammatory tinea Bacterial infections, e.g., folliculitis Viral infections, e.g., varicella
Neoplastic	Cutaneous T-cell lymphoma
Hereditary or Congenital	Darier-White disease Hailey-Hailey disease Inflammatory linear verrucous epidermal nevus (ILVEN)
Others	Xerosis, eczema craquele Senile pruritus Anogenital pruritus Itching in scars Nostalgia paresthetica Amyloidosis, mucinosis Postburn and poststroke pruritus Fiberglass dermatitis Aquagenic pruritus

Top

Categories of Pruritus Therapy

Causal therapy	Identification and treatment of the underlying disease
Symptomatic treatment	Patient education Elimination of provocative factors Topical therapy Corticosteroids for inflammatory conditions Calcineurin inhibitors, e.g., tacrolimus (Protopic^®) and pimecrolimus (Elidel^®) Crotamiton (Eurax^®) Moisturizers Systemic therapy Antihistamines Sedation can be of benefit, especially in eczema Corticosteroids Physical modalities: e.g., phototherapy UVB UVA PUVA

Top

Treatment of Specific Skin Disorders

Atopic Dermatitis

Moisturizing is extremely important for replenishing the skin’s water content and preventing water loss. Maintaining the barrier to keep out exacerbating factors from the skin, such as the external environment, is beneficial. Moisturizers should contain the following: emollients, humectants, occlusives, soothing agents and anti-irritants.

Oral antihistamines, especially those with sedating properties, e.g., hydroxyzine (Atarax^®) or diphenhydramine (Benadryl^®) may provide benefit for patients with pruritus. An antidepressant with potent antihistaminic properties, doxepin (Sinequan^®), can also be useful. The role of histamine in eczema is questionable. Alpha hydroxy acids can reduce scaling and roughness.

Urticaria

Histamine release has a central role in urticaria. There are many causes of urticaria that can be investigated by an allergist. Oral antihistamines, either sedating or nonsedating, are beneficial. Nonsedating antihistamines, such as loratadine (Claritin^®), desloratadine (Aerius^®), or fexofenadine (Allegra^®), can be used in combination with sedating antihistamines at bedtime.

Winter Itch

The cold, dry air of Canadian winters increases transepidermal water loss and causes xerosis (severely dry skin).
As we heat our homes, especially with electric heat, it reduces the humidity in the air.
The skin tries to maintain an equilibrium, also causing an increase in transepidermal water loss.
All ages can be affected.
Can exacerbate underlying skin diseases associated with pruritus, which in turn can exacerbate pruritus further.
Minimize soap. Nonsoap cleansers can be helpful (e.g., emulsifying ointment, Spectrogel^®, Cetaphil^®).
Petrolatum depositing moisturizing body washes and in-shower moisturizers (e.g., Olay^® Ribbons) can be helpful .
Moisturizing after a bath is extremely important.

There is new evidence to show that moisturizers containing niacinamide and glycerin (e.g., Olay^® Quench) not only hydrate the skin, but improve the skin's resistance to external factors and improve the barrier function. Glycerin is required for moisturizers to work quickly and add moisture to the skin, but the niacinamide helps to sustain that benefit over a longer period of time.

Top

Management

Treat underlying cause of pruritus
Cleansing

petrolatum depositing in-shower body washes helpful

Moisturizing

beneficial for most itchy disorders

Antihistamines

sedating and nonsedating (sedating is necessary for atopics)
helpful for symptomatic relief

Topical 5% doxepin cream

useful in neurodermatitis

Capsaicin 0.025% cream, e.g., Zosterix^®

used in postherpetic neuralgia

Topical menthol and camphor lotion

best in adults
not well tolerated in children

Crotamiton cream or lotion

beneficial for scabies

Topical anesthetics such as EMLA^®

useful in neurodermatitis

Calcineurin inhibitors such as tacrolimus or pimecrolimus

approved for atopic dermatitis

Systemic therapy such as ultraviolet B or narrowband
UVB or PUVA

pruritus in pregnancy or systemic causes of itchiness

Topical corticosteroids

most inflammatory skin diseases

Topical Vitamin D3 analogs, e.g., Dovonex^®

antipsoriatic

Cholestyramine and colestipol resins used to control pruritus in patients with cholestatic liver disease.

Top

Conclusion

The causes and differential diagnoses are as diverse for pruritus as the treatment and management are nonspecific. This makes the workup of nonspecific itch difficult. With careful history and physical exam, as well as some laboratory investigations, most serious disorders can be ruled out and the patient's itch can be relieved.

Other articles from this issue: