Merck Manual

Please confirm that you are a health care professional

honeypot link



James G. H. Dinulos

, MD, Geisel School of Medicine at Dartmouth

Last full review/revision May 2021| Content last modified May 2021
Click here for Patient Education
Topic Resources

Ichthyosis is scaling and flaking of skin ranging from mild but annoying dryness to severe disfiguring disease. Ichthyosis can also be a sign of systemic disease. Diagnosis is clinical. Treatment involves emollients and sometimes oral retinoids.

Ichthyosis differs from simple dry skin (xeroderma) by its association with a systemic disorder or drug, inheritability, severity, or a combination. Ichthyosis can also be much more severe than xeroderma.

Inherited ichthyoses

Inherited ichthyoses, which are characterized by excessive accumulation of scale on the skin surface, are classified according to clinical and genetic criteria (see Table: Clinical and Genetic Features of Some Inherited Ichthyoses). Some occur in isolation and are not part of a syndrome (eg, ichthyosis vulgaris, X-linked ichthyosis, lamellar ichthyosis, congenital ichthyosiform erythroderma [epidermolytic hyperkeratosis]). Other ichthyoses are part of a syndrome that involves multiple organs. For instance, Refsum disease and Sjögren-Larsson syndrome (hereditary intellectual disability and spastic paralysis caused by a defect in fatty aldehyde dehydrogenase) are autosomal recessive conditions with skin and extracutaneous organ involvement.

A dermatologist should assist in diagnosis and management, and a medical geneticist should be consulted for genetic counseling.


Clinical and Genetic Features of Some Inherited Ichthyoses


Inheritance Pattern/ Prevalence


Type of Scale


Associated Clinical Findings

Ichthyosis vulgaris




Usually back and extensor surfaces but not intertriginous surfaces

Usually many markings on palms and soles


X-linked ichthyosis

1:6000 (males)

Birth or infancy

Large, dark, usually coarse (may be fine)

Prominent on neck and trunk

Normal palms and soles

Corneal opacities

Lamellar ichthyosis (an autosomal recessive congenital ichthyosis)



Large, coarse, sometimes fine

Most of body

Variable palm and sole changes

Hypohidrosis with heat intolerance

*Congenital ichthyosiform erythroderma (an autosomal recessive congenital ichthyosis)

Autosomal recessive (mutations spontaneous in about 50% of cases)



Thick, warty

At birth: Redness and blisters

In adulthood: Scaling

Most of body

Especially warty in flexural creases

Bullae, frequent skin infections

* This disorder is also called bullous congenital ichthyosiform erythroderma, or epidermolytic hyperkeratosis.

Acquired ichthyosis

Ichthyosis may be an early manifestation of some systemic disorders (eg, leprosy [Hansen disease], hypothyroidism, lymphoma, AIDS, multiple myeloma). Some drugs cause ichthyosis (eg, nicotinic acid, triparanol, butyrophenones). The dry scale may be fine and localized to the trunk and legs, or it may be thick and widespread.

Biopsy of ichthyotic skin is usually not diagnostic of the systemic disorder; however, there are exceptions, most notably sarcoidosis, in which a thick scale may appear on the legs, and biopsy usually shows the typical granulomas.

Treatment of Ichthyosis

  • Minimization of exacerbating factors

  • Moisturization and keratolytics

  • Sometimes infection prophylaxis

When ichthyosis is caused by a systemic disorder, the underlying disorder must be treated for the ichthyosis to abate. Other treatments of ichthyosis include emollients and keratolytics and avoiding drying (1).

Moisturization and keratolytics

In any ichthyosis, there is impaired epidermal barrier function, and moisturizers should be applied immediately after bathing. Substances that are applied to the skin may have increased absorption. For example, hexachlorophene products should not be used because of increased absorption and toxicity.

An emollient, preferably plain petrolatum, mineral oil, or lotions containing urea or alpha-hydroxy acids (eg, lactic, glycolic, and pyruvic acids), should be applied twice daily, especially after bathing while the skin is still wet. Blotting with a towel removes excess applied material.

Ichthyosis typically responds well to the topical keratolytic propylene glycol. To remove scale (eg, if ichthyosis is severe), patients can apply a preparation containing 40 to 60% propylene glycol in water under occlusion (eg, a thin plastic film or bag worn overnight) every night after hydrating the skin (eg, by bathing or showering); in children, the preparation should be applied twice daily without occlusion. After scale has decreased, less frequent application is required. Other useful topical agents include ceramide-based creams, 6% salicylic acid gel, hydrophilic petrolatum and water (in equal parts), and the alpha-hydroxy acids in various bases. Topical calcipotriol cream has been used with success; however, this vitamin D derivative can result in hypercalcemia when used over broad areas, especially in small children.

Retinoids are effective in treating inherited ichthyosis. Oral synthetic retinoids are effective for most ichthyoses. Acitretin (see Other systemic treatments) is effective in treating most forms of inherited ichthyosis. In lamellar ichthyosis, 0.1% tretinoin cream or oral isotretinoin may be effective. The lowest effective dose should be used. Long-term (1 year) treatment with oral isotretinoin has resulted in bony exostoses in some patients, and other long-term adverse effects may arise.

Pearls & Pitfalls

  • Oral retinoids are contraindicated in pregnancy because of their teratogenicity, and acitretin should be avoided in women of childbearing potential because of its teratogenicity and long duration of action.

Infection prophylaxis

Patients with epidermolytic hyperkeratosis may need long-term treatment with cloxacillin 250 mg orally 3 or 4 times a day or erythromycin 250 mg orally 3 or 4 times a day, as long as thick intertriginous scale is present, to prevent bacterial superinfection from causing painful, foul-smelling pustules. Regularly using soaps containing chlorhexidine may also reduce the bacteria, but these soaps tend to dry the skin.

Treatment reference

Key Points

  • Ichthyosis may be acquired or inherited as an isolated disorder or as part of a syndrome.

  • Evaluate patients with gradual-onset ichthyosis for an underlying systemic disorder.

  • Emollients that speed the shedding of skin (keratolytics) are effective in treating ichthyosis.

Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Professionals also read

Test your knowledge

Pressure Injury
Pressure ulcers (PUs) are defined as areas of necrosis and ulceration where tissues are compressed between bone and hard surfaces, such as a bed or chair. There are many risk factors for PUs, which include age > 65 years, decreased mobility, and impaired sensation, among others. Of the main factors that influence the development of PUs, which of the following contributes to PUs but is not a direct cause?  
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest