Por qué pica el eccema - y cómo detenerlo

Why does eczema itch?

Changes to the skin barrier

Dr Derrick Phillips, a consultant dermatologist and British Skin Foundation spokesperson, says the skin barrier - the outermost layer of skin - is different in people with eczema¹. "In eccema, there is an impairment of the skin barrier, leading to increased water loss and dry, itchy, skin," he says. "It is not always possible to identify a trigger for sudden flares of eczema however stress, infections, sweating, changes in the weather, chemicals (for example, chlorine) and allergies can all aggravate eczema."

Usually, the skin barrier protects the skin underneath from irritants and stops water loss, keeping it hydrated. However, in people with eczema, genetic changes - specifically to a gene called filaggrin - make the skin barrier less effective at keeping moisture in. Therefore, the piel becomes drier, which makes it itchy.

Also, because the cells aren't able to retain water as well, they shrink. This causes gaps to open up between the cells, in which substances can enter and cause irritation and itchiness.

Chemical messengers

Another reason why eccema is so itchy is because the skin is affected by substances called chemical mediators². These stimulate the nerve endings in the upper layers of the skin. These nerves tell the brain that there is an itch, making us scratch.

Sudoración

People with eczema are more sensitive to sweat, which makes itching worse, but the reasons behind this are complicated. Firstly, the salty residue left behind after sweating can cause irritation.

Secondly, it is thought that people with eccema have higher levels of chemical mediators called neuropeptides, which can inflame the skin and cause itching³. Research also suggests that people with eczema have a different composition of sweat than those without the condition - and that their sweat contains fewer moisturising properties⁴. Also, studies suggest people with eczema sweat less, which can lead skin to become drier and itchier⁴.

Factores ambientales

Chemicals in shampoos, soaps, perfumes, cleaning products and other substances can irritate the skin, making us want to itch. Other environmental factors, such as the temperature, pollen, animal fur and dust can also worsen symptoms of eccema. These can cause an immune response as the weakened skin barrier means they can get deeper into the layers of skin.

Psychological factors

Itching can also be caused by something called a psychogenic itch. This means the itch is brought on by psychological factors, such as estrés or being in the habit of scratching.

How to cope with eczema itching

Use the right products

Moisturisers play a key role in managing eccema and there are lots on the market to choose from. Phillips says: "I recommend using ointments at night. They are greasy and may be cosmetically unacceptable for daytime use, but they are extremely effective at repairing the skincare barrier and locking in moisture overnight."

During the day, Phillips recommends creams for daytime use as they have a higher water content and are absorbed quicker. Some creams contain extra ceramides to repair the skin barrier.

You should apply when needed throughout the day, but remember that applying it thickly can block pores and lead to more irritation, so it may be better to put it on often but lightly. Don't rub it into the skin, as this can make itchiness worse.

When washing, use products that are recommended by your doctor for eczema, such as your usual emollient. Apply the product like you would with a soap and then rinse it off, before patting the skin dry with a towel and reapplying it.

Top Tips:

Cool moisturisers

Keep moisturisers in the fridge. When they are then used on the skin, they are nice and cool and can help with the itchy feeling!

Use cotton bedsheets

Itching can be worse at night, when you’re trying to relax. Use cotton sheets as they are breathable, absorb sweat and help you stay cool. Wash the bedcovers frequently to get rid of dust and dead skin that build up.

Cover children's hands at night

For babies and young children, try cotton gloves or mittens to stop them scratching overnight. Some sleepsuits have mittens attached.

Try other techniques instead of scratching

You may find it helpful to press a nail onto the skin or tap the skin gently instead of scratching. If the itching is bad, try holding a bag of frozen peas wrapped in a towel to the skin to cool it down.

Stay cool

Getting too hot and sweating can make eccema symptoms worse. Wear several light layers made of cotton, so you can take one off if you feel too warm.

Antihistamínicos

Algunos los antihistamínicos can be used to help the itching. Choose non-drowsy ones for the daytime. If sleep is affected by itching, sometimes the more drowsy antihistamines can help with both itching and sleep.

Hable con su médico

If your eczema symptoms are getting worse or you are finding it hard to manage them, speak to your doctor to make sure you're using the right treatments. You may need to use topical steroids, which are put onto the skin. Your doctor may recommend steroid-sparing creams - medicines that are gentler than esteroides tópicos - for sensitive areas.

Light therapy - the use of ultraviolet light - may be recommended. UV light appears to reduce the number of cells involved in the inflammatory response, which plays an important role in eczema and can reduce itching and soreness. However, this isn't the same as the UV light found in sunbeds, which can lead to cáncer de piel. Only specialist clinics and hospitals offer UV light therapies.

Lectura adicional

1. Agrawal et al: Skin barrier defects in atopic dermatitis.

2. Ruzicka et al: Role of inflammatory mediators in atopic eczema.

3. Zhang et al: Current views on neuropeptides in atopic dermatitis.

4. Tamagawa-Mineoka et al: Atopic dermatitis: Identification and management of complicating factors.