Dermatographia (dermographism): symptoms, causes and treatment

Dermatographia is a skin condition in which firmly stroking, rubbing or scratching the skin makes raised, red, itchy marks appear along the line that was touched. It is also called dermographism, dermatographism or "skin writing", because it is possible to "write" on the skin with a finger. Allergy UK lists it under the term urticaria factitia, which can be caused by rubbing, scratching or scrubbing the skin.

It is classed as a form of urticaria, or hives. NICE Clinical Knowledge Summaries describes chronic inducible urticaria (previously called physical urticaria) as urticaria that occurs in response to a physical stimulus, and lists dermatographism among its types alongside cold, heat, solar, aquagenic, cholinergic, delayed pressure, vibratory and contact urticaria. The British Association of Dermatologists says inducible urticarias often occur in otherwise healthy young adults but can affect any age.

Patient.info says often no treatment is necessary, and in mild cases no extra treatment may be needed. Once it is clear what causes the rash, it may be possible to avoid situations that trigger it. For example, dermographism can often be prevented by avoiding firm pressure against the skin as much as possible.

Many types of hives are helped by antihistamines. Patient.info says the most commonly used are cetirizine, fexofenadine and loratadine, which do not usually cause drowsiness, and that a doctor may advise higher than the usual recommended dose to control the rash. It adds that if the itch makes it difficult to sleep, a sedating antihistamine at night is sometimes used, and that antihistamines are not usually advised in pregnancy. If an antihistamine is taken as soon as the rash appears it tends to fade more quickly, and for frequent rashes a regular dose may be advised.

NICE CKS says people with urticaria requiring treatment should be offered a non-sedating antihistamine to be taken daily, with options including an alternative non-sedating antihistamine, a higher dose under clinical judgement, calamine lotion for itch, and referral to a dermatologist or immunologist if the response is inadequate. Patient.info says steroid tablets do not help physical types of hives, unlike most other types.

The NHS hives page lists scratching or pressing on your skin, such as wearing itchy or tight clothing, among the triggers for hives, and suggests trying to find out what triggers it for you so you can avoid them. Patient.info says a cool bath or shower may ease the itch, and that calamine lotion or menthol 1% in aqueous cream can help with itching.

Patient.info lists tips that some people find helpful, while noting there is little proof they work in everybody: avoid tight clothes if wheals occur where clothing presses, keep cool and keep the bedroom cool at night, and avoid things that make symptoms worse such as alcohol, hot baths, strong sunlight and emotion. The BAD advises not taking aspirin, ibuprofen or other NSAIDs, or opiates such as codeine, unless essential, as they may aggravate urticaria, and avoiding heat, tight clothes and alcohol.

• Avoid firm rubbing, scratching or pressure on the skin where you can.

• Wear loose, soft clothing and avoid tight waistbands, straps and belts.

• Keep cool: avoid very hot showers and baths.

• Use a cool bath or shower, calamine lotion or menthol in aqueous cream for itch.

• Check with a pharmacist or GP before using aspirin or anti-inflammatory painkillers.

• Try to keep a diary of when the rash appears and what you were doing.

Patient.info describes the rash as developing on areas of skin that have been firmly stroked, following the line of the "writing" on the skin. The affected skin is usually very itchy, although in some mild cases it does not itch much. Any part of the skin can be affected, but the palms, soles, genital skin and scalp are less commonly affected.

The weals are red, raised and itchy, and appear within minutes. The BAD says weals and red marks often appear as lines at the sites of scratching and generally last for less than an hour. In many cases the pressure needed to cause the rash is quite firm, although some people develop it with light pressure.

Each rash fades quickly, typically within an hour according to the BAD and Patient.info. The underlying tendency lasts longer. Patient.info says it most commonly first develops in early adult life, and that in most cases it tends to improve gradually over a few years and goes or becomes less severe, although some cases remain troublesome for longer.

Because it can come and go, a diary of triggers can help you and your doctor decide whether treatment is needed.

Hives happen when something causes histamine and other chemicals to be released in the skin. The NHS says this is known as a trigger, and lists scratching or pressing on your skin, such as wearing itchy or tight clothing, among them, alongside heat, cold, stress, infections and medicines.

The sources reviewed do not describe why some people's skin reacts in this way. Patient.info says dermographism is more prone to occur when hot, for example after a hot shower. Triggers vary between individuals.

The BAD says aspirin, ibuprofen and other non-steroidal anti-inflammatory drugs, and opiates such as codeine, may aggravate urticaria. Patient.info lists aspirin, anti-inflammatory painkillers and angiotensin-converting enzyme (ACE) inhibitors as medicines that may be triggers, and advises seeing a doctor if you think a medicine is making symptoms worse, as a change in medication may be an option. Do not stop a prescribed medicine without advice.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if hives do not improve after 2 days, the rash is spreading, hives keep coming back, you also have a high temperature and feel unwell, or you also have swelling under your skin, which might be angioedema.

Call 999 if your lips, mouth, throat or tongue suddenly become swollen, you are breathing very fast or struggling to breathe, your throat feels tight or you are struggling to swallow, your skin, tongue or lips turn blue, grey or pale, you suddenly become very confused, drowsy or dizzy, or someone faints and cannot be woken up. These can be signs of a serious allergic reaction.

The sources reviewed describe dermographism mainly in young adults, but the NHS hives advice applies to children too: a pharmacist can give advice on antihistamines, though treatment might not be suitable for young children. The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you are worried about your child's hives, and always to call 111 if you need help for a child under 5.

Most people with dermatographia are managed in primary care by a pharmacist or GP. The NHS says if hives do not go away with treatment you may be referred to a skin specialist (dermatologist), and NICE CKS says referral to a dermatologist or immunologist is considered if the response to first-line treatment is inadequate.

Private dermatology or allergy opinions are available, but allergy tests are not usually needed, as NICE CKS says investigations are not usually required to diagnose urticaria. Allergy UK and the British Association of Dermatologists provide patient information.