What Is the Difference Between Hives and a Rash?

Hives and rashes both affect how your skin looks and feels. Hives (urticaria) are outbreaks of discolored bumps. They’re caused by allergies or allergy-like skin reactions to irritants. Hives are a type of rash. There are many other types of rashes. A rash causes patches of redness, swelling, itching, or pain and can develop for many reasons, including certain skin diseases, bug bites, or infections.

Since so many factors can cause a rash, it’s common to have one. For example, researchers found that 20% of the population has contact dermatitis—rashes caused by contact with an allergen or irritant. The specific rash of hives is common, too, with about one in five people experiencing it at some point in their lives.

While hives are a type of rash, other types of rashes may be pretty different. Other rashes have various causes, symptoms, and treatments. Knowing whether hives or another type of rash is affecting you can be key to getting the relief you need.

Symptoms of Hives vs. Rash

Hives are itchy clusters of red, white, or flesh-colored bumps that form on warm, red, or discolored skin. Eruptions of hives can also cause areas of swelling. Unlike hives, other rashes don’t always itch. Instead, they may cause pain, swelling, and blisters. Rashes can appear as rosy, red, purple, or discolored skin patches. On darker skin, affected areas become purple or gray.

How extensive and severe hives or other rashes become varies. Most rashes and hives cases are acute—meaning they eventually resolve on their own—though hives can become chronic, lasting six weeks or more. 

If you have hives or another rash, you may experience the following symptoms:

Differences

Hives are a type of rash, but hives can still differ from other types of rashes. These differences have to do with how the rashes spread, their causes, as well as treatments.

Some Rashes Are Contagious

If you have hives, the bumps may spread and join together to form areas of slightly raised skin. However, hives aren’t contagious—they cannot be spread from one person to another.

Other rash types, such as those due to chronic autoimmune skin conditions like eczema or psoriasis, aren’t contagious either. However, some rashes can be spread from person to person.

Viral infections, like measles and varicella zoster virus (chicken pox), that cause rash spread in infected air droplets. Meanwhile, impetigo, a bacterial skin infection, and ringworm, a fungal infection that causes ring-like rashes, can be spread through direct contact.

There Are Different Risk Factors

Hives and other rashes affect people of all ages, but their risk factors differ. For hives, risk factors include:

• Being younger than 5
• Being assigned female at birth
• Having a personal history of allergy, a family history of hives, current autoimmune diseases, or elevated stress

Infants and children can have a lower risk for certain chronic rash-causing conditions, including psoriasis. Smoke or pollution in the air, harsh soaps, and other skin conditions also raise the risk of developing rashes, as can asthma, hay fever, or family history of these conditions.

Hives and Rash Have Different Triggers

Although there is some overlap, the triggers of hives and other rashes can differ.

For instance, contact dermatitis causes rash due to irritation, heat, or direct physical contact with an allergen or toxic substance. Certain shampoos, soaps, fragrances, and beauty products can cause these rashes, as can topical antibiotics, latex gloves, poison ivy or oak, certain fabrics (like wool), and nickel.

Heat, skin irritation, and latex gloves can also trigger hives. However, unlike other rashes, hives are primarily an allergic or allergic-type reaction. They're a systemic response to certain foods and medications, bug bites, pet dander, and pollen. They can also be triggered by anxiety or stress.

Similarities

Since hives are a type of rash, it’s natural that there be some overlap between the two conditions. The diagnosis and treatment of these conditions look similar, they share some triggers, and both can become chronic (long-term) conditions.

The Same Tests May Be Used for Diagnosis

Even though hives and other rashes are distinct conditions, diagnosis typically involves similar assessments and tests. In diagnosing one, healthcare providers often have to rule out the other. Sometimes, physically assessing affected areas is sufficient. Other times, additional diagnostic methods are needed to determine the cause of your rash. These methods can include:

• Allergy testing: A healthcare provider will test your skin’s reaction to allergens to detect or rule out cases of contact dermatitis or other types of allergic rash.   
• Blood tests: Since rashes can arise due to conditions like autoimmune diseases or infections, tests of certain blood proteins and cell types help healthcare providers diagnose.
• Skin biopsy: In some cases, a healthcare provider will collect a sample of affected skin and send it to a laboratory for testing to detect infections or other causes of symptoms.  

Heat Can Trigger Both Hives and Rash

Heat can lead to outbreaks of hives and certain types of rash.

Hot temperatures are among the triggers for hives. Some people may experience solar urticaria, which is hives caused by direct sun exposure.

Heat or sweat rash, known as miliaria, arises as sweat builds up within the skin due to blocked ducts. More common among infants and in hot climates, the skin rash stings or gets itchy and can form red bumps.

Hives and Rash Can Become Chronic

While most with hives and rash don’t have chronic cases, long-term cases are possible with both.

Chronic hives occur when the symptoms last for six weeks or more. These cases are rarer—about 20 of every 100,000 Americans. The symptoms may also go through periods of activity and remission that lasts months at a time.

Other rashes may be chronic. For example, eczema and psoriasis typically have periods of symptoms (flares) and non-activity (remission).

Autoimmune Conditions May Cause Hives or Rash

Some rashes develop due to autoimmune conditions like eczema and psoriasis. In these conditions, the immune system is overactive and attacks healthy cells. This causes inflammation, which can lead to rash. Your skin may become dry, cracked, scaly, sensitive, and itchy.

Some cases of hives may also be a sign of an autoimmune disorder. Thyroid disease, Grave's disease, and Hashimoto's disease are some of the autoimmune conditions that have been tied to chronic hives. Hives may begin even years before diagnosis of the autoimmune condition.

They Share Some Treatments

While there are some differences in how healthcare providers treat hives compared to other kinds of rash, there is some overlap. For hives, home therapies, topical or oral corticosteroids, oral antihistamines, and biologic medications may all play a part in more severe cases.

Corticosteroids and biologics can also treat chronic rash due to eczema or other conditions.

Antihistamines are best reserved for rashes. Providers may also prescribe calcineurin inhibitors, immunomodulating drugs called Janus kinase (JAK) inhibitors, or other injectable medications for different rash types.  

Can You Have Both Hives and Rash?

Hives are a type of rash. In other words, if you have hives, you have a rash. However, it’s also possible to have hives and other types of rash. In fact, eczema can cause hives flare-ups, and evidence suggests the autoimmune condition raises the risk of chronic hives. In addition, certain allergens can trigger both hives and eczema flares.

Because hives and other rashes can resemble one another, distinguishing them is critical for diagnosis and treatment.

When To Seek Care and Who to Contact

If you have hives or another type of rash, there are several signs you need medical help. These include:

• Worsening or lingering symptoms despite treatment
• Pain or itching that is uncomfortable and disrupts daily life
• Symptoms that affect your ability to sleep and perform daily tasks
• Signs of infection, including swelling, pain, or fluid discharge

While rashes can be distressing and uncomfortable, they typically aren’t a sign of a medical emergency. However, hives can be a sign of allergic shock (anaphylaxis)—a potentially fatal, all-body response to an allergen. If you have hives and are experiencing any of the following symptoms, get emergency:

• Lightheadedness or fainting/loss of consciousness
• Difficulty breathing or shortness of breath
• A feeling as though your throat has tightened or you have difficulty swallowing
• Swelling in the face or tongue  

Generally, primary care physicians can diagnose hives or other rashes. They may refer you to specialists, such as a dermatologist (skin specialist) or allergist (allergy specialist), to guide treatment and management.   

A Quick Review

Hives and rashes are common skin conditions. Hives, a type of rash, cause patches of red skin and welts. Rashes can appear in many different ways but typically involve distinct changes in skin color and texture.

Hives are usually an allergic-type reaction, whereas other rashes can arise due to everything from infections to heat or irritation. That said, hives and other types of rash share some traits. For instance, treatments and triggers can overlap.

Persistent hives or rash, as well as worsening symptoms or signs of infection, require medical attention. A primary care provider or dermatologist can help determine if your rash is hives or something else.