A-Z OF SKIN

Pruritus with no rash

Pruritus with no rash

What is “pruritus with no rash”?

Pruritus means itch.

Itch is a very common symptom of skin disorders such as eczema, scabies, insect bites and hives. These skin disorders are characterised by the presence of a rash.

Some people will have pruritus without a skin disorder. These individuals are often referred to as having “pruritus with no rash.”

What causes “pruritus with no rash”?

“Pruritus with no rash” may be due to:

  • Systemic disorders – these are conditions that affect internal organs including:
    • Kidney failure especially in individuals on dialysis
    • Liver disease such as primary biliary cirrhosis
    • Blood disorders such as iron deficiency, polycythaemia rubra vera, lymphoma and myeloma
    • Hormonal dysfunction especially over- or under-active thyroid
    • Infections such as HIV infection
    • Advanced cancer.
  • Neurologic disorders – these are conditions that may affect the:
    • Peripheral nervous system, including brachioradial pruritus, notalgia paraesthetica and post-herpetic neuralgia
    • Central nervous system, including some strokes, multiple sclerosis and brain tumours.
  • Psychogenic disorders – these are mental health conditions including:
  • Medications – drugs may cause pruritus by various mechanisms including drug allergy, drug-induced dryness, sun-sensitivity and liver dysfunction. This includes not only prescription medications but also over-the-counter medications, supplements, herbal remedies and traditional Chinese medicines. It is very important that you let your doctor know if you are taking any of these.

What does “pruritus with no rash” look like?

The natural human response to itch is to scratch the skin. The act of scratching at the skin unfortunately causes more itch, which is then followed by more scratching and further itch. This vicious cycle is known as the “itch-scratch cycle”.

The changes seen on the skin in “pruritus with no rash” are due to scratching and rubbing. These changes include:

  • Hyperpigmentation (brown marks) / hypopigmentation (pale marks)
  • Skin thickening and skin lumps
  • Scratch marks, open sores and scabs
  • Bruising
  • Scarring.

How is “pruritus with no rash” diagnosed?

The diagnosis is usually made by a dermatologist and is based on a medical history (including review of current medications) and skin examination. A skin biopsy may be needed to exclude an underlying skin disorder as the cause of the itch. Skin scrapings and swabs may be needed if an infestation or infection is suspected. A “pruritus screen” is typically ordered to identify any underlying disease of the internal organs. This may include a combination of blood, urine, stool and radiographic tests.

How is “pruritus with no rash” treated?

There are three general principles for treating “pruritus with no rash”.

  1. Identify and treat any underlying cause.
  2. General anti-pruritic measures.
  3. Specific anti-pruritic therapies.

The most important of these principles is to identify any underlying cause and reverse or treat this cause, if possible.

General anti-pruritic measures include:

  • Minimise skin damage caused by scratching and rubbing. It may help to keep the fingernails trimmed short or to wear cotton gloves overnight.
  • Reduce stress. It may help to learn behavioural interventions to avoid scratching in order to interrupt the “itch-scratch” cycle. Some people find psychological support useful, whilst others find meditation, yoga, hypnosis or exercise helpful.
  • Avoid all environmental aggravators of pruritus such as overheating, drying of the skin and prickly/rough materials in contact with the skin.
  • Avoid all soaps, bubble baths, shower gels etc, as these dry the skin and aggravate itch. Use a soap-free wash instead.
  • Use a moisturiser all over the skin at least twice daily and more often if the skin feels dry.
  • Use a “cooling” menthol-containing moisturiser on itchy skin as often as is needed.

Specific anti-pruritic therapies include:

  • Topical treatments (creams)
  • Oral treatments (tablets)
    • Antihistamines
    • Tricyclic antidepressants, such as doxepin or amitriptyline
    • Newer antidepressants, including paroxetine, duloxetine, mirtazepine or sertraline
    • Anticonvulsants, such as gabapentin or pregabalin
    • Naltrexone
    • Aprepitant
    • Many other oral treatments reported, including cyclosporine and thalidomide.
  • Phototherapy
    • Narrowband UVB.

What is the likely outcome of “pruritus with no rash”?

The outcome depends on the underlying cause of the pruritus and whether this can be treated and/or reversed.

This information has been written by Dr Bernadette Ricciardo
Updated 03/11/2017