Is It Hives or a Rash? Here’s How to Tell the Difference

Easily confused by the difference between hives versus rashes? You’re not alone. Considering how similar they look, it’s common to get them mixed up.

“The term ‘rash’ generally applies to an inflammatory skin condition, so hives are a type of rash,” says Jennifer Segal, MD, founder of Metropolitan Dermatology Institute, in Houston. However, much like a square is a rectangle but not the reverse, not all rashes are hives. “Hives are a very common skin condition that results from the allergic immune response to a wide variety of triggers, including medicines, illnesses, allergies, foods, heat, cold, and even stress,” says Dr. Segal.

We spoke with skin experts to get the scoop on how to differentiate between hives versus rashes, as well as how to treat them—and, hopefully, how to prevent them from coming back.

(Related: 7 Reasons You Get Hives on Your Face)

What is a rash?

“A rash is any kind of eruption on the skin. There are literally hundreds if not thousands of kinds of rashes,” says Kelly Bickle, MD, a board-certified dermatologist in Santa Monica, California. One of the most common rashes is eczema, a group of conditions otherwise known by their various names—including atopic dermatitis, contact dermatitis, and seborrheic dermatitis. Eczema affects up to 17 per cent of Canadians, according to the Canadian Dermatology Association. When the skin’s barrier (the outermost layer of your epidermis) isn’t functioning properly, your skin can flake and become scaly which can result in an eczema rash.

Psoriasis is another common skin condition—affecting about one million Canadians, according to the Canadian Dermatology Association. It often appears as a rash and is frequently caused by an infection or stress.

Meanwhile, rosacea affects more than 3 million Canadians, according to the Canadian Dermatology Association. It can cause you to have redness on your face, as well as red spots or bumps and flushing of the skin.

(Related: What Is Skin Writing? Everything You Need to Know)

Are hives a type of rash?

Medically known as urticaria, hives are red, swollen skin patches triggered by histamine release, says pediatric dermatologist Sheilagh Maguiness, MD, an associate professor in the department of dermatology at the University of Minnesota Medical School and co-founder of Stryke Club skin care line for teen boys. The area is also often itchy, she adds. Unlike other types of rashes, which can last for days, weeks, months, or even years, hives frequently last no more than 24 hours. However, in some instances, hives can be chronic—meaning they reoccur for longer than six weeks, explains Papri Sarkar, MD, a dermatologist in Newton, Massachusetts.

The causes of hives are varied, but typically the same triggers pop up over and over, including stress, extreme temperatures, medicine, infections, and allergic reactions to foods, pets, and pollen, says Jeffrey Fromowitz, MD, a board-certified dermatologist in Boca Raton, Florida. If you see raised areas or have especially itchy patches on the skin, you’re probably dealing with hives. “Hives are a very distinctive type of rash with raised, welt-like lesions,” says Dr. Segal. By contrast, rashes aren’t always itchy, depending on what type of rash it is.

(Related: 8 Summer Health Hazards Canadians Face Each Year)

What do hives look like?

Hives are distinguishable by their telltale appearance, says Dr. Segal. Expect them to feel itchy and to look red and raised. “Hives are typically raised pink or red welt-like lesions that are either localized in one area or generalized over the whole body,” she explains. “They are typically itchy and occasionally warm—generally uncomfortable.” They may also be the same colour as your skin, unlike rashes (which will generally be only red).

(Related: Stop Scratching and Try These Natural Home Remedies For Hives)

Can hives be dangerous?

Hives are extremely common, but severe hive reactions that tend to have a hereditary or genetic source are rare, says Dr. Segal. Still, in some cases, hives can be dangerous and lead to swollen lips or a swollen tongue, which can affect breathing and require immediate medical attention.

Chronic hives aren’t as dangerous, but they’re still troubling, explains Dr. Segal. “Some people are more prone to hives and have a lower threshold for reacting to environmental stimuli. The hives can either be fairly continuous or wax and wane—such as worsening or improving seasonally or based on location,” says Dr. Segal.

If you have chronic hives, see your doctor to diagnose the underlying cause: likely allergies or an autoimmune disorder, although stress is another common trigger.

What does a rash look like?

Rashes vary depending on the type of underlying skin condition. For example, a shingles rash will probably not look the same as, say, a psoriasis rash. Still, rashes do tend to have certain identifiable characteristics. “Rashes are usually defined by changes in colour or texture of the skin,” says John Shaff, board-certified physician’s assistant at Stockton Dermatology in Phoenix. “Rashes don’t always itch either, unlike hives.”

On the other hand, similarly to hives, certain types of rashes may itch excessively, especially if the rash stems from something irritating such as poison ivy. Other rashes, such as shingles—also known as herpes zoster—may even be painful.

How to treat hives and rashes

Although both hives and rashes generally require similar treatment, there are subtle differences in how you treat hives versus rashes, according to dermatologists.

Hives

There are many different ways to treat hives, but generally, the line of first defense is oral antihistamines, says Dr. Segal. Medications—such as Benadryl, Zyrtec, or Claritin—are most effective when continuously taken. Equally important: identifying the root cause of the hives, in order to potentially eliminate any triggers. Some hives are caused by friction or pressure, such as clothing that’s too tight, while others are launched by sun exposure, says Dr. Sarkar, naming only a few of many causes. By pinpointing what’s causing the hives, you can prevent future outbreaks. This may include wearing looser, more breathable clothing, in the case of friction-based hives, or by avoiding sunlight and staying in the shade, if you have sun-induced hives.

Another common cause of hives has to do with extreme temperature changes, in particular the cold—known as cold urticaria. Antihistamines also can be used to block cold urticaria, as they’re triggered by histamine release, explains Dr. Segal. Finally, studies have pointed to a link between stress, exacerbated skin conditions, and inflammation, so attempts to lessen stress certainly can’t hurt—and might even help.

(Related: 8 Sun Care Tips from a Dermatologist)

Rash

Rash treatments vary and depend on the type of rash, and what’s causing it. “Rashes can be treated in many ways, but differ depending on the cause,” says Shaff. “Most often a topical steroid is used to help, but this isn’t always the case. If the rash is caused by something the person came in contact with, then that needs to be removed.” Because some rashes are caused by an illness or infection, by contrast, the rash won’t go away until the underlying issue is identified.

“The illness or infection needs to be treated and the rash will usually resolve with that,” says Shaff. Treating a rash is best done under the care of an experienced medical provider, says Dr. Segal. “The rash must be correctly identified and diagnosed in order to treat it appropriately. Treatments can vary from as simple as avoidance of triggers to systemic medications and even more intensive testing,” says Dr. Segal. She emphasizes that a correct diagnosis is essential to finding your best treatment option. “Inappropriate treatment can worsen certain conditions rather than improving them,” she says.

For more answers to your skin related questions, read up on Psychodermatology: Could It Give You Better Skin?