Skin serves a vital purpose as the barrier that protects the inside of the body. It is filled with special cells of the immune system that can protect the body and skin from viruses, bacteria, and other hidden threats.

Once the skin cells detect any type of suspicious substance, they trigger a reaction that causes the area to become inflamed. Medical professionals refer to this inflammation as a rash or dermatitis. This can lead to itching.

Immune cells can react to something that touches the skin, a whole-body infection, or an illness. Some rashes are inflamed, painful, and irritated, while others can lead to blisters or patches of raw skin.

Itching is a symptom common to many skin complaints. Skin can itch all over the body or only in specific areas.

Here are some specific causes of pruritus:

Dry skin

When the skin loses too much water, it can become dry. Those with excessively dry skin can experience a nearly constant itch.

Common signs and symptoms of dry skin include:

• rough, scaly, or flaking skin
• excessive itching
• gray or ashy-looking skin in people with dark skin
• cracks in the skin that are prone to bleeding
• chapped or cracked skin or lips

Environmental factors leading to dry skin include excessively hot or cold weather with low humidity. Washing too much can also cause dry skin.

A good moisturizer can usually help relieve symptoms of dry skin. Extremely dry skin can be a warning sign of dermatitis, so it may be necessary to see a dermatologist to help get relief and keep the condition from worsening.

It is important to seek help to treat very dry skin because cracks in the skin can allow germs to enter and lead to an infection. Inflamed, sore spots on the skin are often an early sign of a potential infection.

A skin specialist may prescribe a special moisturizer to apply throughout the day or a topical medication to apply directly to the skin.

Learn about what causes patches of dry skin.

Eczema

Eczema, or atopic dermatitis, is a common cause of skin rash in children.

The American College of Allergy, Asthma & Immunology (ACAAI) reports that eczema affects 10–20% of children but only 1–3% of adults.

A person’s genes and immune system may play a role in the development of eczema.

With eczema, there are gaps in the skin barrier. These gaps in the skin barrier allow:

• moisture to escape from the skin, which leads to dryness
• dust mites and fragrances to enter the skin, leading to inflammation
• viruses and bacteria to enter the skin, leading to infection

A person can work with a dermatologist to develop a treatment plan to control eczema. A treatment plan will involve a skin care plan and ways to manage triggers. Treating eczema can help to:

• ease symptoms
• reduce flare-ups
• prevent eczema from worsening
• reduce the risk of infection
• keep the skin hydrated

Learn moreLearn more about how to treat eczema:

• How to treat atopic dermatitis
• Top 16 natural remedies for eczema

Allergies

Irritation and allergic reactions can also cause itchy skin. Allergic contact dermatitis occurs when the skin directly comes into contact with an allergen.

A person with irritant or allergic contact dermatitis will develop an inflamed, itchy rash that can include small blisters or bumps. The rash arises whenever the skin comes into contact with the allergen, a substance the immune system attacks. There can be a time delay between exposure to the allergen and when the rash occurs.

Touching clothing, pets, chemicals, soaps, and substances such as poison ivy or cosmetics can trigger allergic reactions. Food allergies can also cause the skin to itch.

Nickel allergies are quite common. When someone comes into contact with jewelry that contains even a small amount of nickel, they can develop inflamed, bumpy, itchy, and swollen skin at the point of contact.

For a person with an allergic reaction to a particular substance, one of the easiest things to do is to avoid that product or substance. Over-the-counter creams or medicated creams can help clear up a rash.

Learn about how allergies develop.

Dehydration

Not getting enough fluids puts the body in a state of dehydration. Dehydration can result in dry skin, which can lead to itching.

A dehydrated person’s skin may look dry, dull, or sunken. Other symptoms of dehydration include headaches, fatigue, and muscle cramps.

A dehydrated person will also notice a reduced amount of urine that might also be darker yellow and stronger smelling. Their mouth will feel dry, and their skin will not bounce back as well when squeezed.

A person can treat mild cases of dehydration by drinking more fluids, especially water. Serious cases require medical attention.

Hives

Hives are a type of skin inflammation caused by the release of a chemical in the body called histamine. This release causes small blood vessels to leak, which causes the skin to swell. Hives can cause uncomfortable itching and be painful. However, they are not contagious.

While hives are not typically dangerous, swelling reactions affecting the lips, tongue, throat, or breathing require emergency medical attention.

There are two kinds of hives:

• Acute hives: These can occur after coming into contact with an allergic trigger, such as a particular food or medication. Non-allergic causes, such as excessively hot or cold weather, sun exposure, or exercise, can also serve as a trigger.
• Chronic hives: Some long-term conditions are associated with hives. In other cases, knowing what is causing a person’s hives is difficult. They can come back regularly for months or even years. Even when a doctor cannot determine the cause, the condition often improves over time.

The ACAAI says that hives affect about 20% of people at some point in their life.