Prurigo nodularis: symptoms, causes and treatment of itchy nodules

BAD explains that pruritus is the word doctors use for itching and prurigo is a word describing the changes in the skin after it has been scratched for a long time. In nodular prurigo these changes look like firm, very itchy bumps. They can improve or resolve when the person stops scratching, but for many people this is very difficult without proper and sometimes prolonged medical treatment.

The bumps are usually darker than the surrounding skin but can also be lighter, flesh coloured, red or pink depending on skin type. They have a rough, thick surface and may have a scab, crust or scratch marks on top. BAD says they are usually less than 1cm across, can feel firm, tender and itchy, and that some areas of skin can break down to form an ulcer. Changes in pigmentation and scarring from deep scratching can also occur.

BAD says the nodules can appear anywhere but are commonly on the outside of the arms and legs, with the back, buttocks, shoulders and chest also affected and the face rarely involved. The mid-upper back is usually spared, which is known as the butterfly sign, because it is hard to reach.

It can occur at any age and in any racial group or gender. It is not hereditary, but atopy can run in families and is associated with nodular prurigo.

BAD says treatments focus on controlling the condition and are aimed at stopping the skin itching. They are usually combined, and a dermatologist will choose according to severity.

BAD’s leaflet says newer treatments were being assessed for nodular prurigo on the NHS. NICE’s technology appraisal TA955, published in March 2024, did not recommend dupilumab for moderate to severe prurigo nodularis in adults when systemic treatment is suitable. NICE said there is no standard care, that care in the NHS usually starts with treatments applied to the skin and adds others as symptoms get more severe, and that the trial evidence was uncertain because the comparison did not include many treatments used in the NHS.

NICE also says that people who started dupilumab in the NHS before the guidance was published can continue without change to funding arrangements until they and their clinician consider it appropriate to stop. Guidance can change, so a dermatologist can say what is currently available.

BAD describes the cause as unknown. Heat and anxiety have both been associated with nodular prurigo, although the exact relationship is difficult to determine. Heat can physically trigger itching, and reducing heat and sweating can reduce itching. Stress can both trigger and be caused by nodular prurigo, and people with prolonged periods of stress are more likely to scratch.

BAD also says nodular prurigo can start after an insect bite in some people, and that several other medical and neuropsychological conditions can be associated with it and may need further investigation.

The NHS notes more generally that itchy skin has many possible causes, including long-term skin conditions such as eczema and psoriasis, and less commonly more serious conditions such as thyroid, liver or kidney problems, which is why a GP may arrange blood tests.

BAD says the symptoms of itching and the typical skin lesions are usually enough to make the diagnosis. If there is doubt, a skin biopsy can be taken under local anaesthetic and examined under a microscope to help confirm it, and blood tests may be done to look for other conditions that can make the skin itchy.

The NHS says you should see a GP if itchy skin is affecting daily life, does not get better with self-care or keeps coming back, or is severe. A GP may refer you to a dermatologist.

BAD calls not scratching the most important but hardest thing to do. It suggests distraction techniques or keeping the hands occupied, mittens or cotton gloves at night, a cool damp flannel, a cooled emollient kept in the refrigerator or one with added menthol, a bedroom temperature of 18 to 20°C with light, breathable bedclothes and a fan during the day if hot and itchy.

It advises layers of cotton clothing rather than wool or polyester, which do not absorb sweat as easily and can lead to overheating and itching. It also warns that emollients can make dressings, clothing and bedding catch fire more easily, even when dried, so people should be very careful near naked flames and cigarettes.

The NHS general advice for itchy skin is similar: pat or tap rather than scratch, hold something cool on the skin, use cool or lukewarm baths and showers, use an unperfumed moisturiser regularly and keep nails clean, short and smooth.

The NHS says to see a GP if itchy skin is affecting your daily life, does not get better with self-care or keeps coming back, is caused by a new rash, lump or swelling that you are worried about, is all over your body, is severe or happens during pregnancy. For nodular prurigo, that includes itching that is disturbing your sleep, work or mood, because BAD says it can be so severe that it causes problems with sleep, work, relationships and mood.

BAD notes that some areas of skin can break down to form an ulcer, so new open or painful areas, or signs of infection such as spreading redness, pus or fever, are a reason to be seen promptly. Less commonly, the NHS says itchy skin can be a sign of a more serious condition, such as thyroid, liver or kidney problems, which is why a GP may arrange blood tests.

Itching in pregnancy is a special case: the NHS says it can sometimes be caused by a liver condition called intrahepatic cholestasis of pregnancy, so check with a GP or midwife.

The NHS route is usually a GP or pharmacist first, then referral to a dermatologist if the condition is persistent or severe. NICE says there is no standard care for prurigo nodularis in the NHS, but that care usually starts with treatments applied to the skin and adds others as symptoms get more severe.

Private dermatology appointments can be quicker, and phototherapy and some prescriptions are also available privately. NICE did not recommend dupilumab for routine NHS use for this condition in March 2024, so ask a dermatologist what is currently available and whether any specialist clinic is involved. Ask for a written plan for creams, bandaging and phototherapy so that your GP and dermatologist work from the same advice.

BAD says the itch can be very distressing physically and psychologically and in some cases so severe that it causes problems with sleep, work, relationships and mood. That is why psychological support appears in the list of treatments. If itch is affecting your sleep or mental health, tell your GP or dermatology team, because that changes how urgently stronger treatment is considered.