Chronic Pruritus: Understanding the Pervasive and Incessant Itch

What is chronic pruritus?

Pruritus is a medical term for ‘itch’. Itch is an uncomfortable sensation that provokes a person to scratch. When the itching lasts more than six weeks, it is termed chronic pruritus [1].

Although itching is not a life-threatening symptom, it can have a profound negative effect on a person’s social life. It can cause difficulty sleeping and an inability to concentrate on work/studies or daily routine. Chronic pruritus can cause emotional distress and is associated with mental health conditions such as anxiety and depression [2]. To make things worse, frequent scratching or rubbing of the affected skin area can lead to injury or impairment of skin tissues, resulting in infections and other health complications.

In this article, we explore these itchy symptoms and explain the possible underlying causes in simple layman's terms. The article strives to educate and empower patients to better understand these common symptoms and seek medical attention when symptoms persist.

How common is chronic pruritus?

Chronic pruritus is a common symptom that can affect anyone at any age or in any walk of life. Approximately 22% of people may experience chronic pruritus throughout their lifetime [3]. The condition is commonly seen in elderly people who are above the age of 65 [4]. In Singapore, nearly half of the elderly may experience chronic pruritus [5].

Ever wonder how a person can feel ‘itchy’ and the need to scratch?

Though the sensation of ‘itch’ is a nuisance, it functions as a body’s self-protective mechanism. It is supposed to warn us against harmful external agents and protect our bodies. The itch sensation is comparable to other skin sensations such as touch, pain, etc.

Itch occurs when the itch-sensing nerve endings known as ‘pruriceptors’ on the skin are stimulated by heat, chemical, mechanical causes, infection, or even inflammation. Once the pruriceptors are activated, the ‘nerve signals’ will be delivered via the C-fibres that are present on the skin to the spinal cord and the brain. When we scratch or rub the affected area, the pain and touch receptors on the skin can also be activated. The concurrent pain and touch sensation can interfere with the itch sensation, resulting in temporary relief. However, the skin can be irritated or injured via scratching, eventually leading to a never-ending vicious itch-scratch cycle [6].

When should I consider seeing a doctor for my persistent pruritus?

You should consider seeing a doctor for further checkups and treatment if your itch:

• Continues for more than two weeks and becomes more persistent.
• Affects more areas of the body or the whole body (generalised).
• Affects your social life, sleep, work, studies, hobbies, and daily routine.
• Has other associated symptoms, such as pain, fever, and weight loss.

What are some questions regarding chronic pruritus?

There are a few key questions that you may want to consider preparing yourself before seeing your doctor to evaluate chronic pruritus further; these are:

• Is there an area that is itchy, or is it non-specific/whole body?
• Is there any activity/timing that makes the itching worse or relieves the itch?
• Is there a visible skin rash?
• Is there associated pain, fever or other unusual symptoms?
• Any new medications that one is taking?

What are the causes of chronic pruritus?

Chronic pruritus is a medical condition that can be tricky for patients and physicians to diagnose and manage.

We can split the causes of a persistent itch into broad categories, such as:

Skin-related 4causes

• Skin diseases: eczema, psoriasis, hives, scars, skin infections (parasites, scabies, molluscum contagiosum, fungal yeast infection, herpes simplex infection), insect bites etc.
• Skin irritation and allergy: chemicals, soaps, plants, and chemicals in contact with the skin leading to a skin reaction.

Skin-unrelated causes

• Underlying medical conditions: thyroid disease, liver disease, kidney disease, diabetes, iron deficiency anaemia, cancers (lymphoma, solid tumour).
• Mental health disorders: depression, anxiety, obsessive-compulsive disorders, delusional disorders.
• Nerve diseases: shingles, nerve impingement, multiple sclerosis, stroke.
• Drug-induced itch: a common side effect of many medications.

In a real-world circumstance, a person may have multiple factors that contribute to experiencing a persistent itch. Unfortunately, sometimes, it may be impossible to pinpoint a single cause of chronic pruritus.

What are the possible complications from chronic pruritus?

Prolonged, unattended itch can lead to a vicious itch-scratch cycle. Out of itch desperation, one may even resort to repeated rubbing and washing to achieve temporary relief of the symptoms. Nonetheless, all these actions can lead to injury of the normal skin barrier, resulting in skin infection or even scarring of the affected area.

Chronic pruritus can be uncomfortable, affecting the quality of social life. It is known that a person with chronic pruritus is predisposed towards mental health disorders such as anxiety and depression.

Furthermore, chronic pruritus can be more than a skin-deep issue. It may suggest underlying medical conditions that, if left unattended, may result in potential long-term systemic complications.

What can I expect from my doctor for chronic pruritus?

It is useful to discuss your symptoms with your healthcare providers. Depending on individual circumstances, your doctor may offer tests such as the ones below to identify the possible trigger of your persistent itch symptoms.

Tests offered may include:

• Blood tests: to screen for liver function, kidney function, thyroid function, iron deficiency.
• Skin tests: to screen for possible skin infection.
• Allergy tests: if there is a concern of an allergy as a cause for the itch.
• Skin biopsy: if there is concern about skin causes/skin malignancy.
• Neurological studies: neurological studies with nerve studies/ MRI may be offered if nerve causes are concerned.

What is the treatment for chronic pruritus?

If there is an underlying condition that causes the recurring of itch, the underlying medical condition needs to be addressed.

Chronic pruritus can be relieved with:

• Soothing menthol-related moisturiser and emollients
• Topical anti-inflammatories such as steroids or calcineurin inhibitors
• Oral antihistamines

You can discuss with your doctor to understand more about the management of chronic itch symptoms.

What have I learnt today?

• Chronic pruritus can be a debilitating, persistent medical symptom that affects a person’s quality of life.
• While chronic pruritus can be related to underlying skin disease, it can be induced by other causes, including disease of the internal organs, nerve disease, psychiatric disorders, and medications.
• Medically investigating the possible triggers of chronic pruritus can aid the treatment outcome of this medical condition.

References

1. SingHealth. (n.d.). What is chronic pruritus? Singapore Health. Retrieved from https://www.singhealth.com.sg/news/singapore-health/what-is-chronic-pruritus
2. Sokolova, A., Rist, L., & Biedermann, T. (2023). Chronic pruritus: A comprehensive review. Journal of the American Medical Directors Association, 23(2), 255-266. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9885286/
3. Kaffenberger, B. H., & Kaffenberger, J. A. (2023). Chronic pruritus: Assessment, diagnosis, and management. JAMA, 330(3), 291-299. https://jamanetwork.com/journals/jama/article-abstract/2819296
4. Kage, P., Ständer, S., et al. (2021). Pathogenesis of chronic pruritus: An overview. Journal of Clinical Medicine, 10(3), 345-356. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7795219/
5. SingHealth Duke-NUS. (n.d.). First local study on elderly perception of chronic pruritus. Retrieved from https://www.singhealthdukenus.com.sg/news/research/first-local-study-conducted-found-how-elderly-perceived-chronic-pruritus-prolonged-itch-and-results-may-help-in-pruritus-management
6. Lavery, M. J., et al. (2022). Itch management: Understanding the itch-scratch cycle and its impact on chronic pruritus. Journal of the European Academy of Dermatology and Venereology, 36(4), 601-610. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8896504/