The why and how of Itching explained

Everyone has suffered from itching sometime or the other. Itching is an unpleasant, irritating feeling or sensation on the skin which urges and makes you scratch. For some, itching is a chronic problem and can be a cause of great distress especially in the night-time compromising sleep and quality of life.

Types of Itching

Itching (medically called PRURITUS plural-Pruritis) can be acute (sudden onset – lasting for a short duration of < 6 weeks) or chronic (has been present on and off, or continuously for > 6 weeks).  Itching can be localized (in particular parts of the body) or generalized (all over the body).  For localized itching, a skin problem (dermatological disorder or disease) is usually the cause, however in generalized itching cases, one may need to investigate for non-skin causes (due to diseases in other organs – also called systemic causes).

Is the Itching due to a skin problem or not?

The most common cause of generalized itching is dry skin, while Eczema is the most common cause of localized itching. Sometimes the skin hardly looks dry but when you scratch across it, to your surprise a white line will appear indicating underlying dryness! Dry skin can occur in all age-groups, increases with age, and is a very common problem in the elderly population. Dry skin is not considered a skin disease per se but can cause a distressing amount of chronic itching disturbing sleep.

Itching, if due to a skin disease may have some obvious signs on the skin like a rash. (Rash is a change in skin color and texture where the involved part of the skin looks red and inflamed, with a patchy or raised appearance, sometimes with blisters, cracks, scales, or swelling). A rash may or may not be painful but is commonly itchy.

Skin diseases causing rashes and itching (tabulated below) are usually localized to particular parts of the body.  Some of these skin disorders may be contagious like Fungal infections, Scabies, Lice, and Herpes, while others like Eczema, Psoriasis, Hives, and Lichen planus are not. Sometimes skin scars from wounds, burns or surgery can also be itchy.

Usually, skin diseases present with a rash before, along with, or just after the itching starts. Most skin diseases have a characteristic pattern and appearance of the rash, which can clinch the diagnosis for a doctor.

However, even if itching is not due to a skin disease, repeated, prolonged and forceful scratching of the skin induces a lot of trauma which can lead to a rash over a period of time, making it look like a primary skin disease by the time you visit a doctor!  So, knowing the timing of the development of rash and itching is of importance!  Also scratching itself causes skin irritation leading to more itching (called the Itch-Scratch cycle).

Apart from dry skin being the cause, generalized itching may not be due to a skin-related cause, and can be a symptom of other organ diseases (systemic causes). These conditions include diabetes, liver, kidney or thyroid disease, anemia, mental health causes like anxiety and depression, and rarely some tumors (like Lymphoma) should be investigated for, especially in the elderly. Some medicines can also have itching as a side effect like those for BP, heart, gout, hormonal treatment, and Opioid pain killers. During pregnancy (and around monthly menstrual time), hormonal changes occur which can in some women be a cause of generalized itching.

What causes itching and why is it pronounced and worse in the night?

Irritation to the nerve endings in the skin is picked up by receptors and relayed as an itch sensation to the spinal cord and brain, which thereafter send back signals which cause us the urge to scratch. The commonest and well studies itch mediator is ‘histamine’ but other mediators are also involved.

Many conditions (both skin and non-skin related) including dry skin, are associated with the itching being significantly more in the night. There are many reasons for this. There is an increase in skin temperature and more water loss from the skin during the late evening and night thereby increasing skin dryness. The levels of our body’s steroid hormones (which reduce itch and inflammation) are lower in the night. There may be more release of certain substances in the evening/night like B endorphins (known to lower pain perception but increase itch sensation), and other mediators of itch and inflammation (enkephalins, IL2, PGD2, PGE2, TXB2).  There are fewer distractions at night, increased mental stress of the day with anxiety, thoughts and analyzing, or depression all of which increase itch perception.

Night-time (Nocturnal) itching impacts sleep and the next day’s performance, and can reduce efficiency in day to day life.

Solutions?

The specific disease (skin or non-skin) is medically treated accordingly once diagnosed. Infections like fungal, herpes, scabies or lice are treated with specific drugs for these infecting organisms.

Moisturizing lotions/creams and oils are first line of management along with lifestyle modification before drugs/medicines.  Many lotion/creams have both moisturizing and anti-inflammatory/anti-itch natural substances which can be not only beneficial for their symptom-relieving and soothing effects but also suitable for long term usage due to the absence of any significant side effects. Some of these substances include coconut oil, colloidal oat meal, aloe vera, tea tree oil, turmeric, honey, wheat germ oil and fulvic acid. Applying such moisturizing lotions/creams, especially at night, bathing in lukewarm water, along with using non-alkaline soaps or bathing oils are effective solutions.

The doctor may prescribe a class of oral drugs called ‘Anti-histamines’ to provide symptomatic relief and also improve sleep. Sometimes stronger medicines (steroids, capsaicin, tacrolimus, and others) may be prescribed by your doctor depending on the type, severity, and response of the particular skin condition. These medicines should never be taken/applied without a doctor’s prescription as their dosing, and usage needs medical supervision to avert/minimize adverse effects. In some cases, light therapy may be an option a dermatologist may offer.

In select cases of generalized itching, psychological intervention and medication in the form of behavioral modification therapy and antidepressant/anti-anxiety medicines can also help under appropriate medical monitoring.

It is important not to cause secondary damage and infection to the skin because of the trauma of recurrent and forceful scratching. Such infections will need the application of antibiotic cream/ointments.

For any query, additional information or to discuss any case, write to info@drvarsha.com, and be assured of a response soon.

References: IJDVL 2017, 62(1):7 and Am Fam Physician. 2011 Jul 15;84(2):195-202

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