What itching is and where it comes from
Itching is the sensation that makes you want to scratch. It can be local or all over the body, short or long-lasting. Most often the cause is in the skin itself: dryness, irritation, an allergic reaction, eczema. Less often itching is the body's response to an illness elsewhere, which is the main reason not to ignore it when it goes on for a long time.
Itching with and without a rash
The first thing a doctor checks is whether the skin looks different. If itching comes with redness, small blisters, hives or flaking, it is usually a skin cause such as dermatitis, eczema, an allergy, scabies or a fungal infection. This group is covered on the Skin rash page.
If the skin looks normal but itches, dryness or irritants are common culprits: hot water, harsh soap, wool clothing. See Dry skin for how to deal with that. Itching with no visible skin change that lasts for weeks is a reason for a work-up.
Itching all over the body
Itching that covers the whole body or large areas is more often tied to general causes: dry skin, medications, allergies, hormonal changes, and sometimes liver, kidney, thyroid or blood conditions. That is why a doctor usually orders blood tests for widespread itching. If you are also losing weight without trying, have night sweats, or your skin or eyes turn yellow, do not wait.
Itching at night
For many people, itching gets worse in the evening and at night. Partly this is normal: skin loses more moisture at night and the body is warmer. Many skin conditions, such as eczema, psoriasis and scabies, also flare at night. Night itching is typical of scabies, so if several family members itch at once, see a dermatologist. Before the visit it helps to keep the bedroom cool, wear cotton, trim nails short and moisturize lightly before bed.
Itching during pregnancy
Mild itching of stretched skin on the belly is common in pregnancy and usually harmless. But strong itching, especially on the palms and soles and worse at night, should not be dismissed. It can be a sign of intrahepatic cholestasis of pregnancy, a liver condition that needs medical assessment. Tell your obstetrician-gynecologist as early as you can instead of waiting for the next routine visit.
Itching in a child
In children, itching most often comes from atopic dermatitis, allergy, insect bites, heat rash or scabies. If your child cannot sleep because of it, scratches until the skin breaks, or has a rash and a fever, see a pediatrician or a dermatologist. Keep the child's nails short and choose soft cotton pajamas.
What you can do before the visit
- Try not to scratch. Broken skin gets infected easily, and scratching makes itching worse.
- Take short, lukewarm showers and use mild fragrance-free products.
- Apply a fragrance-free moisturizer to slightly damp skin after washing.
- Put a cool compress on the itchy area.
- Note when itching gets worse and after what, which helps the doctor.
- Do not start allergy pills or steroid creams on advice from the internet. They are not always needed and can mask the rash.
How a doctor looks for the cause
The doctor starts by asking where and when it itches, what has changed in recent weeks, which medications you take and whether anyone close to you itches too. Then the skin is examined. If nothing explains it, blood tests are common, including a general count and checks of liver, kidney and thyroid function, and an allergist may be added if an allergy is suspected. Treatment follows the cause: moisturizing, anti-inflammatory creams, treatment for parasites, or treating the underlying illness.