Across clinical settings, pruritus (or itch) challenges care outcomes, can be hard to treat, and impacts on quality of life, mental health and mortality. The reason we itch is to protect the skin against noxious stimuli; scratching or rubbing disrupts the irritant. However, too much scratching can inflame the skin and often the cause of pruritus is not an external stimulus at all.
Accompanying many dermatologic conditions due to peripheral stimuli, pruritus also arises from systemic disease (renal, hepatic, endocrine), malignancy and medications – all of which may present as skin disorders, but actually originate in the central nervous system. Pruritus without obvious primary skin lesions should be investigated for an underlying cause.
Whatever its origins, scratching further inflames skin, stimulates nerve fibres, initiating the itch-scratch cycle. As the patient scratches, they damage the skin leading to the release of inflammatory chemicals, which increases the itchy sensation. The itch-scratch cycle alters the structure of the skin by compromising the barrier effect, which can then result in prurigo nodularis or lichenification. As such, assessing and treating itch as early as possible is an important facet of effective patient care.
When assessing pruritus, the following categories will help identify what the underlying cause might be:
- Dermatologic – an itch associated with skin conditions
- Systemic – driven by organs other than skin (eg uremia, cholestasis)
- Neurogenic/Neuropathic – related to the central and peripheral nervous systems, nerve compression or nerve irritation
- Psychogenic – no dermatologic cause with a psychological component
Varied causes suggest multiple mechanisms may induce pruritus. Sensory nerve endings in the epidermis and dermal-epidermal junction are stimulated by chemical mediators such as histamine, opioids, serotonin and prostaglandins. Signals are transmitted along unmyelinated, histamine-sensitive and insensitive peripheral C-nerve fibres (as opposed to C-nerve fibres that transmit pain), which causes the sensation of an itch.
Pruritus characteristics will provide clues to the origin and will indicate the most effective treatment options.
- Is the itch acute? Something triggers it and a “scratch” usually relieves it.
- Or is it chronic? Present for more than six weeks and not relieved by scratching.
- Is it a rash that is itchy or an itch without a rash?
- Is the itch localised or generalised? Generalised and severe pruritus demands evaluation for systemic disease, which will mean blood tests, physical examination and possibly imaging.
Determining the underlying cause of pruritus and individualising treatment will require a nursing assessment, which should include a full history as well as a skin examination.
When performing a skin examination ensure that you use adequate lighting to inspect the skin texture and any subtle lesions that may be present. Pay attention to affected and non-affected skin, including web spaces and skin folds. Primary lesions that are unaltered by scratching may indicate a dermatological cause while secondary lesions only (eg excoriations) suggest a systemic cause. Make a note of lesion distribution and contributing conditions, such as dry skin.
When taking the patient’s history the “OLDCARTS” mnemonic formula will help to guide and order your collection of information.
- Onset – when did it start?
- Location – localised or generalised? Initial location, progression, distribution (some aetiologies display pruritus in favoured sites)?
- Duration – acute or chronic?
- Character – stinging or burning?
- Aggravating factors – environmental, treatments prescribed or over-the-counter medication?
- Relieving factors – environmental, treatments prescribed or over-the-counter medication?
- Timing – is the itch consistently present or does it come and go? Is it seasonal or related to the time of day? Has it been experienced previously? Are there circumstances surrounding appearance such as illness, travel or contacts?
- Severity – is it so severe that it disrupts sleep?
Be sure to add a detailed medication history, including over the counter medications, natural remedies, new prescription medications and current medications where the dose has been altered.
The first line of management for mild, localised pruritus are topical therapies. Systemic strategies are added depending on severity and extent. These should be employed in conjunction with the removal of aggrevating external factors.
- Encourage cooler, shorter showers.
- Moisturise immediately after bathing in order to improve barrier function and maintain the acid mantle.
- Cool compresses will relieve heat and assist with hydration of the skin
- Wet dressings applied with moisturiser can be soothing, but caution must be applied in older people and people with infected skin.
- Cut fingernails or wear gloves at night to avoid further scratching.
- Sleep in a cooler environment to avoid overheating.
Additional measures that might be applied depending on the underlying cause:
- Topical antipruritics such as menthol or oatmeal.
- Oral antihistamines, although consider the sedating effect.
- Topical corticosteroids.
- Phototherapy with a dermatologist’s referral.
Pruritus commonly causes physical and psychological distress. Individual evaluation with considered methodical care and management will help to aid this complex issue and provide much needed relief to your patient.
For further reading, see ‘How to Describe a Rash – A List of Terms and Corresponding Images‘
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