Dry and itchy skin can be a challenging presentation for GPs, and is often symptomatic of other conditions. This article looks at the common causes as well as other skin conditions associated with pruritus.
Common dermatological causes
Other skin conditions associated with itch
Systemic causes of dry, pruritic skin
General approach for management of a patient with dry skin/pruritus
There’s no doubt that itch (pruritus) and dry skin are common and troublesome dermatological complaints. Pruritus is defined as an unpleasant cutaneous sensation that provokes the desire to scratch.1 Although figures vary, itch has been reported to be a prominent symptom in between 8% and 42% of patients with a skin problem.2,3 Despite being a prevalent complaint, little is known about the underlying pathophysiology of itch, but it is likely to involve both peripheral and central mechanisms. While histamine is a known mediator of itch, the sensation can also be induced by various agents, including prostaglandins, cytokines and drugs such as opiates. These provoking factors – and others – explain how antihistamines are unable to provide relief to all forms of itch. Pruritus is considered to be acute when it lasts for less than 6 weeks, and chronic if lasts for over 6 weeks.
Xerosis (dry skin) is a common cause of intense pruritus in elderly patients due to greater water loss through the skin. This increases the chance of the skin cracking, which ultimately leads to pruritus. It is often much worse during the winter months due to patients spending time in overheated, dry rooms, or sitting too close to a fire or radiator. The pruritus associated with dry skin often presents on the back, flank, abdomen and waist, and results in asteatotic eczema on the lower legs and resembles ‘crazy paving’.
Both dry skin and pruritus are major features of numerous skin diseases, and often evidence of these signs in specific areas of the body offer clues to the likely diagnosis. Some of the more common skin diseases for which dry, itchy skin is a major symptom and the areas typically affected are described in Table 1.
This presents as pink or white raised areas of skin, termed wheals (weals), surrounded by an inflamed base which resembles nettle rash. The wheals can last for a few minutes or up to 24 hours and are invariably pruritic.
Often the cause of urticaria is unclear, but a careful history may elicit one of the many known causes which include:
- Cold (i.e. exposure to cold air, water, ice)
- Sun exposure
- Certain foods, e.g. milk, eggs, shellfish
- Some medicines (e.g., aspirin, non-steroidal anti-inflammatory drugs, opiates and rarely statins)
- Delayed pressure urticaria due to pressure on the skin for extended periods of time carrying heavy bags or pressure from a seat belt.
Due to the mite Sarcoptes scabiei, the first symptom is pruritus, which arises several weeks after infestation with the mite and is characteristically worse at night. Check for the presence of burrows (seen as 0.5 to 1.5 cm grey and irregular tracks in the finger web spaces, palms and wrists, armpits, buttocks and nipple areas). A hypersensitivity rash to the mite faeces, characterised by inflamed papules on the trunk and limbs, develops several weeks after infestation. However, the itch can precede the development of the rash.
This is much less common and characterised by pruritic vesicular lesions affecting the elbows, knees and lumbosacral spine.
If a cutaneous cause for dry skin and pruritus cannot be established, then it may be due to one of many systemic diseases. Reassuring factors that make a systemic cause less likely include acute onset and localised pruritus. A more generalised pruritus, due to a systemic cause, has a more insidious onset.5 There are several potential causes and the most common ones are discussed in this article.
As many as 40% of patients with chronic renal failure receiving haemodialysis experience pruritus.4 The precise mediators of pruritus in patients with chronic renal failure are unclear but elevated levels of plasma bile acids and increased vitamin A in the skin are potential contributing factors. Clinically, many patients have generalised pruritus, though just over half report that the itching is localised, mainly affecting the back, abdomen, head and arms.5
Impaired secretion of bile (cholestasis) is a common symptom in several forms of liver disease, and is associated with pruritus. Although the prevalence of pruritus varies with the underlying disease, up to 80% of patients with primary biliary cirrhosis experience pruritus.6 Clinically, cholestatic pruritus is worse in the evening, and though it can be generalised, patients report that itch affects the limbs as well as the palms and soles. The itch is worsened by psychological stress, heat, and contact with certain fibres such as wool.
Endocrine disorders such as hypothyroidism are associated with dry, coarse skin and hair. In contrast, patients with hyperthyroidism have thin, soft and warm skin, though pruritus may be present. Diabetes mellitus is often reported to be associated with pruritus, though in practice it is rarely a problem. Moreover, in recent guidance from the British Association of Dermatologists, it was recommended that patients with generalised pruritus should not undergo routine endocrine testing, e.g. thyroid function tests and fasting glucose levels for diabetes, unless there are other clinical signs which are suggestive of these disorders.7
Iron deficiency can lead to the presence of generalised dry skin and pruritus, though a less common pruritic disorder is polycythaemia vera. In fact, pruritus is an important clinical feature in as many as 42% of patients with polycythaemia vera,8 and an intense pruritus without the development of skin lesions is often triggered by contact with water (aquagenic pruritus), irrespective of the water temperature.
Pruritus can be induced by pregnancy from several different dermatoses,9 though an uncommon cause in the third trimester is intrahepatic cholestasis.
The presence of pruritus due to malignancy may be because of a localised effect on tissue or due to a systemic reaction to the malignancy termed, paraneoplastic itch. It is commonly caused by lymphoproliferative malignancies such as multiple myeloma and Hodgkin’s lymphoma and in some cases, the generalised pruritus may precede the diagnosis of the disease.10
Neurogenic and psychogenic pruritus
A neuropathic pruritus is caused by a primary lesion or dysfunction along the afferent pathways of the nervous system. In contrast, psychogenic pruritus is considered to be of psychiatric origin.11 Neuropathic pruritus can be caused by conditions such as multiple sclerosis and post-herpetic neuralgia, whereas psychogenic pruritus has several causes including depression, anxiety and mania.
Other possible causes of dry skin and pruritus
Some infectious diseases such as HIV can lead to pruritus, though this is often due to the co-existence of dermatological conditions such as xerosis and seborrheoic dermatitis. Conditions such as lice can cause pruritus, and it is estimated that 5% of all cutaneous adverse drug reactions lead to pruritus. Potential pruritus-inducing drugs include anti-malarials, ACE inhibitors, statins, anti-epileptics and opioids.12
Clearly, an important first step is to establish a history of the dry skin and itch. This will include duration, onset, frequency, specific location (or whether it is a more generalised problem), together with possible provoking and relieving factors. Given that itch is a prominent feature in many skin conditions, it is necessary to enquire about the presence of any previous cutaneous disease and/or the existence of atopy.
A full medical and drug history will also help eliminate or identify possible causes. Furthermore, historical findings that might help the diagnosis include:
- Recent use of new cosmetics or creams/hobbies/occupational exposure – indicating an allergic/contact dermatitis as a potential cause
- New medicines – representing a possible cause of urticaria or a fixed drug eruption.
It is also useful to explore the nature of the pruritus, and this may also serve to help establish the diagnosis as described in Table 2.
Examination of the skin
A full examination of the skin is necessary to determine whether or not there is a likely cutaneous cause. In the absence of a rash, look for secondary lesions such as excoriations, prurigo nodules or papules, lichen simplex chronicus (thickened areas of skin) as well as signs of bacterial infection.
Other specific features include pallor, glossitis and angular cheilitis in those with iron deficiency, a ruddy complexion around the lips, cheeks and nose in those with polycythaemia vera.
Patients with a systemic cause, such as Hodgkin’s disease, may have hyperpigmentation, ichthyosis and non-tender lymphadenopathy and splenomegaly.
Given that there are a wide range of potential systemic causes of dry skin and pruritus, it is worth undertaking a standard biochemical screen, which will include:
- Full blood count/ferritin
- Urea and creatinine
- Liver function tests
- Thyroid function test.
Other investigations warranted will depend on the results of the clinical examination.
If there is a systemic cause, then treating the underlying condition may help alleviate the dry skin/pruritus.
Prior to initiating any treatment, general self-care advice – which is applicable to either a cutaneous or systemic cause – would include limiting bathing/showering times to less than 20 minutes and using cool or lukewarm water rather than hot water, which can have a drying effect on the skin. Patients should be advised to keep indoor temperatures cool rather than too warm, as this might irritate the skin. Additionally, advise patients to wear fabrics that do not irritate the skin (such as cotton), and avoid wool and denim which can provoke skin irritation.
Emollients are an effective first-line therapy for patients with dry/pruritic skin and should be used liberally and frequently in quantities of up to 500g per week. There are a wide range of products available and it is important to find one that is acceptable for the patient and which can also be used as a soap substitute. Patients should be advised to apply their emollients immediately after a bath or shower to help keep moisture on the skin.
If an emollient does not help to relieve the pruritus, then addition of an active 0.5 to 1% menthol may be of value.
Systemic agents include a short-term (two week) trial of a sedating anti-histamine such as hydroxyzine 25mg at night or chlorpheniramine 4mg at night. However, the efficacy of oral antihistamines may be limited if the cause of the pruritus is systemic.
If the dry skin or pruritus has not responded to either topical emollients or sedating oral antihistamines, referral to a specialist is warranted. However, a referral should always be made if there is no obvious cause for the dry skin/pruritus or if it is associated with other red flag signs such as weight loss.
Dr Rod Tucker
Community pharmacist, Researcher with a special interest in dermatology, East Yorkshire