Pruritus or itch, defined as the desire to itch, is a common feature of inflammatory skin disease. It has many causative factors, such as, eczema or psoriasis, allergic reaction with the release of histamine, iron deficiency, imbalanced thyroxine levels, renal disorders or failure, and as a complication of diabetes. For some individuals, this condition may be so bad that their general health deteriorates because they can no longer sleep without disturbance due to the itch. This then leads to a diminished quality of life (Peters, 2019). Patients on anticoagulant therapy may have bruised or excoriated skin from the mechanical action of the scratching on thinner skin. The appearance of their skin is quite dramatic and the skin is sore, both of which can be upsetting for the patient. The mechanical reaction of the epidermis to repeated trauma from scratching can also lead to lichenification, or thickening of the skin. With lichenification, the skin lines become more raised from the surface and the skin becomes drier. Inflammatory cells remain active and this leads perpetuates the itch scratch cycle (National Institute for Health and Care Excellence, 2019). A quarter of patients with chronic kidney disease suffer from pruritus, and despite topical leave-on treatment, their skin condition only improves after a renal transplant (Healy and Sahota, 2007).
Medication and pruritis
Certain medication for long-term conditions causes this distressing side effect, for example, ACE inhibitors and beta-blockers taken for hypertension, angiotensin-II receptor antagonists, and hydroxychloroquine sulphate taken for rheumatoid arthritis. In cases in which it is present without a rash or any previous skin history in older adults, it is important to investigate and rule out a metabolic or tumour cause before reviewing the medication the patient is taking for a long-term condition. The drug history should include any new medication or anything the patient has taken over the counter or borrowed. If the medication is stopped and the itching stops, then a clear cause has been established, but it does mean that if the medication is essential, the patient has no other choice but to take it, in order to obtain the optimum clinical benefits.
The health professional and the patient have to decide what is more important, and it may lead to a disagreement or the patient failing to take their medication regularly. The presentation of pruritis may also indicate poor control or failure to take prescribed medication, for example, in patients with hyperthyroidism or hypothyroidism (Healy and Sahota, 2007).
Treatment considerations
Scratching can provide temporary relief from the itching but can cause or maintain mechanical damage to the skin. It also lowers the threshold for pruritus once the skin begins to heal. This produces a strong positive reinforcement for further scratching, which prevents healing or a break in pattern (Daunton et al, 2016). If the causative medication is essential, then rotating through emollients, antihistamine tablets, a course of phototherapy or even low-dose prednisolone may be helpful to enable the patient to live with the pruritus. Topical antihistamine, for example, doxepin hydrochloride, can be used with good effect, as it reduces the sensation of itch within 15 minutes (Millington et al, 2018).
Conclusion
It is essential to understand how distressing itch can be to patients, and it is important that health professionals provide patients the tools and information to enable them to look after themselves and thus improve their quality of life and health.