O que causa coceira na pele?

Common causes of itching

Coceira is a symptom, not a medical condition. It's usually caused by a stimulus in your skin. For instance, with insect bites you're reacting to saliva injected at the site of the bite. With nits, you can develop an allergy to the head lice (the itching isn't due to them biting). If a local cause is to blame, you'll usually have a rash.

Sometimes, though, a sensation of itching comes from messages sent by your brain - these tend to cause itching all over your body. For instance, icterícia (caused by liver problems) and doença renal crônica can both cause itching. However, if you feel otherwise well and don't have any other symptoms like yellow skin or severe tiredness, this is unlikely. If you've recently started a new medicine and develop itching, speak with your pharmacist or GP

Dermatite is the medical term for any inflammation of the skin. Eczema, commonly found in children, is a kind of dermatitis. It causes dry, inflamed skin and sometimes intense itching. In children, it's most commonly seen on the front of the elbows and the backs of the knees. Anyone can get 'irritant dermatitis' from chemicals (eg, in cleaning fluids, detergents, some plants) - this most commonly affects your hands, as they're most often in contact with the chemicals.

'Contact dermatitis' is caused by allergy to whatever you touch. The tiniest contact can cause an itchy, inflamed red rash. Nickel jewellery or belt studs, cosmetics and preservatives in creams can all be to blame. You may need a referral for 'patch testing' to see what the culprit is, and must avoid all contact in future.

A very serious allergic reaction called anafilaxia causes sudden, intense all-over itching as well as swelling of your lips/tongue/throat, shortness of breath, palpitations, and collapse. Causes include food (especially nuts), insect stings and medicines. It's not common but definitely a medical emergency.

Treatment very much depends on the cause. For instance, if you have all-over itching, your doctor will do exames de sangue for conditions like anemia and thyroid, kidney or liver disease. Local itchy rashes caused by allergy or inflammation often respond to fortes.

If you do suffer from itching, there are lots of ways you can help yourself.

Tame your talons

Keep your fingernails short - it reduces damage to your skin if you do scratch an itch. Cotton gloves at night can help too.

Stay cool

You may be among the few who don't revel in the prospect of spring tripping its way brightly towards summer, as staying cool relieves itching. Lukewarm baths or showers can help. So can having separate bedclothes from your other half, so you can stay cool even if they want to snuggle under a thick duvet. Wear breathable clothes - ideally cotton - and avoid woollen clothes, especially next to your skin.

Go fragrance-free

Scented bubble baths, soaps and even shampoos can irritate sensitive skin - talk to your pharmacist about a non-irritant soap substitute such as aqueous cream. Keep a small pot of this in your handbag to use when you're out if you get itchy hands.

Moisturisers are great but you may need to apply them several times a day for best effect. Water, oddly, can dry your skin out, so always put moisturisers on after bathing. Again, your pharmacist can advise on unscented ones which won't irritate your skin.

Try not to scratch!

While it can be horribly hard to resist the urge to scratch, never forget the 'itch-scratch' cycle! Scratching may seem blissful at the time, but it leads to chemicals being released under your skin which can make you feel even itchier. That chemical, by the way, is histamine - which is why antihistamine tablets can help many (but not all) types of itch so much. If itching is stopping you sleeping, a 'drowsy-making' antihistamine like chlorphenamine (Piriton) can be a good option.

Com agradecimentos à revista 'My Weekly', onde este artigo foi originalmente publicado.