Itch (Pruritus)

You may assume that every itch is an allergy, or that the strongest cream or antihistamine will treat it. Itch has many possible causes. It may begin in dry or inflamed skin, follow an infection or infestation, result from a medicine or occasionally reflect a condition elsewhere in the body. Treatment depends on the pattern and cause.

Pruritus means itch Pruritus is the medical term for an unpleasant skin sensation that creates the desire to scratch. It may be localised to one area, widespread, constant, intermittent, worse at night, associated with a visible rash, or present without an obvious rash. Itch is a symptom rather than a diagnosis. Assessment follows its pattern, effect and possible cause. Scratching can create an itch–scratch cycle Scratching may provide brief relief, but it can damage the skin barrier, increase inflammation, cause more itching, produce bleeding or crusting, thicken the skin, introduce infection, or disrupt sleep. Once scratching changes the skin, it may become difficult to identify what the original rash looked like. Reducing skin damage is therefore part of treatment even before the precise cause is known. Dry skin is a common cause Dry skin may appear rough, flaky, cracked, ashy, tight, or less visibly red on brown or black skin. It may be worsened by cold weather, low humidity, hot baths, frequent washing, harsh soap, age related skin changes, or some medical treatments. Regular emollients can restore moisture and support the skin barrier. Inflammatory skin conditions often itch Common examples include eczema, contact dermatitis, psoriasis, urticaria, and heat rash. The pattern, distribution, surface texture and triggers help distinguish them. Redness may be less obvious on darker skin. Inflammation may instead appear purple, grey, dark brown, ashy, thickened, or more raised than surrounding skin. You should describe what has changed from your usual skin rather than relying on the word "red". Contact dermatitis follows exposure Contact dermatitis occurs when something irritates the skin or triggers an allergic reaction. Possible triggers include soap, cleaning products, fragrance, cosmetics, hair products, gloves, metals, adhesives, plants, or workplace chemicals. The rash often corresponds to the area of contact, although allergic reactions may spread beyond it. A product that has been used safely for years can still become a trigger. Hives may appear suddenly Urticaria, also called hives, causes raised itchy swellings that may move, disappear and reappear. Individual swellings often last less than a day, although new ones may continue to form. Possible triggers include infection, medicines, foods, insect stings, temperature, pressure, or no identifiable trigger. Hives alone may be uncomfortable but are different from anaphylaxis. Swelling of the tongue or throat, breathing difficulty, faintness or circulatory collapse requires 999. Infection or infestation can cause itch Possible causes include scabies, head lice, pubic lice, fungal infection, thrush, insect bites, or bacterial infection of damaged skin. Scabies often causes severe night time itch and may affect finger webs, wrists, waist, genitals, hands, or feet. Other household or close contacts may also itch. Treatment usually needs to include relevant close contacts and environmental instructions to prevent reinfestation. Not everyone who itches at night has scabies. The visible rash may be caused by scratching When itch comes first, you may later see linear scratch marks, crusting, small bleeding points, thickened skin, areas of altered pigmentation, or broken skin. Your clinician may look for areas that are difficult to reach, because sparing there can suggest that scratching created much of the visible rash. Medicines may trigger itching Itch can begin after a new prescription, a dose increase, a non prescription medicine, a supplement, or an injection or infusion. The medicine may cause a skin eruption, hives, dryness, liver disturbance, a nerve related itch, or an allergic reaction. Do not stop an essential medicine without advice unless emergency guidance tells you to do so. Record the medicine name, when it was started and whether other symptoms appeared. Widespread itch may arise beyond the skin When itch is widespread and there is no clear primary rash, clinicians may consider liver or bile flow disorders, kidney disease, thyroid disease, iron deficiency, diabetes, blood disorders, nerve disorders, medicine effects, or pregnancy related conditions. Most widespread itch does not indicate a dangerous internal illness. However, persistent unexplained itch may require examination and blood tests. Additional symptoms guide assessment Tell a clinician if itch occurs with yellow skin or eyes, dark urine, pale stool, abdominal swelling, weight loss, fever. Night sweats, enlarged glands, marked fatigue, increased thirst or urination, numbness or burning, a new lump, or generalised bruising or bleeding. These features do not identify one diagnosis, but they may change which tests are needed. Itch during pregnancy needs particular attention Itch is common during pregnancy and often has a straightforward skin cause. However, very severe itch, especially affecting the palms or soles and becoming worse at night, may indicate intrahepatic cholestasis of pregnancy. Contact your maternity unit urgently, or NHS 111 if you cannot reach it, when this pattern occurs. Do not wait for a rash. Cholestasis can cause intense itch without a visible primary rash. Localised itch may require examination of that area Examples include itch affecting the scalp, eyelids, ears, genitals, anus, hands, or feet. Possible causes differ between sites. Persistent genital or anal itch may relate to dermatitis, infection, leakage, inflammatory skin disease or another local condition. Examination is often more useful than repeated over the counter treatment. General measures can reduce itch You can consider short, lukewarm showers, fragrance free washing products, regular unperfumed emollient, loose cotton clothing, cool compresses, keeping nails short. Patting or pressing rather than scratching, avoiding overheating, using clean gloves at night if scratching occurs during sleep, and identifying repeated personal triggers. Use a separate clean spoon or pump for emollients supplied in tubs to reduce contamination. Use emollients regularly An emollient may be applied after washing, whenever skin feels dry, in the direction of hair growth, and without vigorous rubbing. Ointments are greasier and often provide more moisture. Creams and lotions may feel lighter. Emollient residue can build up on clothing and bedding and increase how quickly fabric burns. Keep treated skin, clothes and bedding away from naked flames, cigarettes and other ignition sources. Antihistamines help some causes, not every itch Antihistamines may be useful for hives and some allergy related conditions. They may have limited effect when itch is driven by dry skin, liver disease, kidney disease, nerve dysfunction, or certain inflammatory conditions. Some antihistamines cause drowsiness and affect driving, work and falls risk. A pharmacist can advise whether a product is suitable, particularly if you are pregnant, older, taking other medicines or have heart, prostate or eye conditions. Steroid creams require the correct strength and duration Topical corticosteroids reduce inflammation in conditions such as eczema. The appropriate strength depends on the diagnosis, body site, age, severity and duration. Strong steroids can damage skin when used incorrectly, especially on the face, genitals or skin folds. Do not use someone else's prescription or continue repeated courses without review. Avoid treating an uncertain rash with several products Using multiple creams can irritate the skin, cause contact allergy, alter the appearance, delay diagnosis, or introduce infection. Take photographs before starting treatment when the rash changes quickly, provided this does not delay urgent care. Your clinician examines both rash and general health Assessment may include distribution, skin surface and borders, scratch marks, burrows, signs of infection, nails and scalp, lymph nodes, abdominal examination, signs of liver, kidney or thyroid disease, and medicine review. Blood tests may be arranged when itch is widespread, severe, persistent or unexplained. Arrange a GP review GP assessment is recommended when itching affects daily life, does not improve with self care, keeps returning, is severe, is widespread, occurs with a new lump, swelling or concerning rash, or happens during pregnancy. A pharmacist may help with mild, localised and uncomplicated itch.

Itch is a sensation produced through interactions between the skin, immune system and nerves. A safe assessment asks whether there is a primary rash or only scratch marks, whether the itch is localised or widespread, whether it started after a new exposure or medicine, whether anyone else is affected, and whether there are systemic, pregnancy or allergy warning signs.