Hives Vs Rash: Key Differences and Treatment

The term “rash” refers to a change in color or texture or both with your skin. Hives are a distinct type of rash that features raised wheals (welts). All hives are rashes, but not all rashes are hives. Treatments for rashes vary based on the underlying cause.

I’m a highly allergic and skin-sensitive gal, so I’ve had a litany of hives and rashes in my time. With sometimes overlapping symptoms, hives and other types of rashes can easily be confused with one another. So what’s the difference?

“Hives (or urticaria) are a distinct type of rash characterized by raised, itchy welts that can appear suddenly, shift location, and usually fade within 24 hours,” says Srdjan Prodanovich, MD, FAAD, a board-certified dermatologist and founder of EZDERM.

“In contrast,” he adds, “‘rash’ is a broader term that refers to any skin change or eruption, including redness, scaling, or inflammation caused by various conditions such as eczema, contact dermatitis, or infections. In short, all hives are rashes, but not all rashes are hives.”

I have a condition called mast cell activation syndrome (MCAS). Mast cells are a type of immune cell. Mine are overactive. My immune system will sometimes perceive something as a threat that isn’t really a threat, such as going from a cold to warm environment. When this happens, my mast cells sometimes release too much of the chemical mediator histamine, leading to raised welts, aka hives.

My sensitive skin is also prone to reactions from contact with irritants, including adhesives, certain detergents, and more, resulting in a rash that isn’t hives. With my experience of both hives and other rashes, I’ve become pretty good at the not-so-fun game of “hives vs rash: which is it?”

This article serves as a head-to-head comparison of hives and other rashes, the common causes, and how to treat.

Understanding skin reactions: hives and rashes

Both hives and other types of rashes result from your immune system reacting to a trigger and releasing chemicals that cause inflammation to help protect the body.

To understand the difference between hives and rashes, we need to unpack what they are. First, as Dr. Prodanovich notes, hives are also considered a rash. But they’re just one type of a rash, which is more of an umbrella term.

“’Rash’ is a broad term that covers inflammation of the skin, including hives, psoriasis, eczema, bumps, and more,” says Melanie Palm, MD, MBA, a board-certified dermatologist at Art of Skin MD. “Hives are a type of rash that are often characterized by red or skin-colored welts. They often feel intensely itchy and sometimes come with a burning or stinging sensation.”

• Rashes occur when an area of skin features a change in texture, color, or appearance; a rash is also called a “sudden skin eruption.” Causes vary, from bacterial or fungal infections, allergic reactions, inflammation and irritation, autoimmune disorders, and more.
• Hives, a type of rash, are also called urticaria; hives are wheals or welts, which are raised areas of the skin. They occur because mast cells have released histamine and other chemicals related to the immune system. Hives usually itch, but not always.

What do hives look like vs. a rash?

Again, hives are a type of rash, but they often look distinct from other rashes because they appear as wheals or welts due to swelling on the surface of the skin. The welts may match your skin color or look blotchy. They can be small, like the size of an erasure on the end of a pencil, or they may be much larger, such as the diameter of a pint glass or even a salad bowl. Their edges can also blend together. They are sometimes circular or more elongated or irregularly shaped.

Rashes are much more complicated to describe because each type of rash varies in appearance, and the same type of rash can look different from one person to the next. A rash might present with a change in hue compared to your usual skin color. A rash may be red, pink, purple, gray, silver, white, or just darker in general. A rash also often features a change in texture, such as bumps, spots, cracks, or scales. However, a rash can also be a smooth but inflamed patch of skin.

How do you know if your rash is hives or if it’s a different type of rash? Imagine you’ve spilled water on a sealed hardwood floor or wooden deck. It beads in irregular shapes on the surface. Hives match this general beading appearance. However, how long your rash lasts and your specific symptoms can offer some additional clues.

Location and duration

Hives and rashes can appear on any part of the body. So location isn’t always a helpful way to distinguish whether you have hives or another type of rash. However, some autoimmune rashes show up in specific locations. For example, a rash related to systemic lupus erythematosus typically appears across the nose and bridge of the cheeks.

Duration can be a bit more helpful. Unless you have chronic urticaria, which lasts or goes away and reappears, the one-off bout of hives tends to go away within 24 hours. Other rashes, however, can last for days, weeks, or even longer, depending on the cause.

Hives also tend to have a sudden onset, meaning they develop quickly, whereas other types of rashes can either appear quickly or gradually over time.

Symptoms to help you tell the difference

Your symptoms can also offer some clues.

• Itching. Hives especially, but also other types of rashes, tend to itch, though this is not always a characteristic.
• Swelling. Hives feature swelling because of blood vessels leaking fluid into the surrounding tissue. Other types of rashes sometimes cause swelling, as well, but again hives always appear as wheals or welts–raised areas.
• Pain or burning. Hives and other types of rashes can also burn; however, these symptoms are more common and severe with shingles rashes and contact dermatitis, an allergic rash.

Common triggers and causes

Any conversation about triggers for rashes and hives should come with an explanation about the term “idiopathic” Sometimes this word, which means the cause is unknown, gets tacked onto the word urticaria, such as in the phrase “chronic idiopathic urticaria.”

That doesn’t mean that the hives are in your head. Obviously, you can see them on your skin. It just means the cause isn’t clear. A knowledgeable and caring provider will not dismiss your symptoms, however. Instead, they will work to get to the root cause.

“In many chronic cases, called chronic idiopathic urticaria,” Dr. Prodanovich says, “no apparent external cause is identified. However, research shows that a significant number of these ‘idiopathic’ cases are linked to autoimmune thyroid disease.”

Other forms of autoimmunity may also be a culprit. Up to 45 percent of chronic urticaria cases have associations with autoimmunity. This was true for my hives, originally deemed chronic idiopathic urticaria. Subsequent testing eventually revealed my MCAS diagnosis, which has links to autoimmunity.

Common triggers for hives

“Hives occur when an allergic reaction triggers the release of histamine into the skin, causing an inflammatory response,” Dr. Palm says.

Common allergy triggers

• Foods (e.g., tree nuts, eggs, shellfish)
• Insect bites or stings
• Pet dander
• Medications (e.g., antibiotics or non-steroidal anti-inflammatory drugs, aka NSAIDs)
• Environmental factors (e.g., bare skin on grass)

Chronic activation of mast cells, causing hives, can also occur from Type 2 helper T (Th2) immune dominance, meaning the immune system is overactive, which leads to an increase in immunoglobulin E (IgE) antibodies that drive allergic reactions. This dominance may occur from exposure to environmental toxins, gut dysbiosis, and more.

And histamine intolerance occurs when the body can’t break down histamine properly, which can lead to a hives eruption.

“Other factors like autoimmune conditions, stress, physical stimuli (for example, sudden temperature changes or exposure to extreme hot or cold), and even sunlight can trigger hives in some people,” Dr. Palm says.

“Stress doesn’t typically cause hives,” Dr. Prodanovich adds, “but it can intensify or prolong them. Emotional or physical stress triggers the release of histamine, which fuels itching and inflammation, and cortisol, which, when chronically elevated, may dysregulate immune function and weaken the skin barrier. I frequently see patients with chronic urticaria experience flare-ups during stressful life events, underlining the connection between psychological stress and skin conditions.”

A subset of hives is called dermatographia. This type appears as a result of pressure, scratching, or rubbing. For example, if a cat scratches me, or even if I scratch myself, I will develop a hive in the shape of the scratch. Just by scratching me, you can literally “write on my skin” which is what the term “dermatographia” means.

Common triggers for rashes

Listing triggers for other types of rashes gets a bit more complicated since they vary depending on the type of rash.

• Allergic reactions
• Autoimmune conditions or autoimmunity (e.g. psoriasis, psoriatic arthritis, etc.)
• Friction (e.g., from clothing)
• Heat (miliaria, a “heat rash” caused by blocked sweat glands)
• Infections
• Injury
• Irritants
• Viruses

Signs you should see a doctor

“You should seek medical attention if hives or rashes last more than a few days, recur frequently, or are accompanied by facial or throat swelling, difficulty breathing, fever, or severe pain,” Dr. Prodanovich says. “These symptoms may indicate a life-threatening allergic reaction (anaphylaxis) and require immediate emergency care.”

Diagnosis and testing

After you talk to a knowledgeable care team, your clinician may ask you questions about your symptoms, examine your affected skin, and ask you about your medical history.

Some testing may be required to determine if you have allergies and, if so, what you are allergic to. In other cases, your provider may request laboratory tests to look at allergic or immune-system markers.

Treatment options for hives and rashes

Your treatment options for hives or another type of rash will depend on the underlying cause. For example, a rash from an infection may require antibiotics or antifungal medications, which may be oral, topical, or both.

If you have an autoimmune disorder that’s causing your skin issues, then your provider will work with you to manage the underlying condition. Treatments may include lifestyle changes, medications, and more.

For short-term relief, you have a few options. “Antihistamines, which are available over the counter, are typically the first line of defense for treating hives,” Dr. Palm says. You can take these orally or apply a topical cream.

Over-the-counter (OTC) hydrocortisone creams are also an option for hives and other types of rashes. However, you should check with a provider first to ensure you’re using an OTC product that’s right for you.

If you know what triggers your rash or hives, avoiding the trigger can be helpful. However, that’s not always possible. For example, I mentioned my odd trigger of going from cold to warm environments. I typically can’t avoid this in winter without simply staying inside all the time. (No thank you!) However, if your hives result from a food allergy or an allergy to a specific detergent or fabric, then avoiding the trigger will reduce the chance of hives recurring.

A functional medicine approach to managing hives and rashes

Functional medicine offers a multilayered approach to treating rashes and hives by addressing the various triggers identified through testing. This integrated treatment strategy typically includes:

• Personalized dietary interventions, including elimination diets and anti-inflammatory nutrition plans
• Gut-healing protocols to restore intestinal barrier function and balance the microbiome
• Targeted supplementation to address nutritional deficiencies and support immune function
• Strategies to address environmental triggers and toxin exposure
• Stress-management and mind-body techniques to address psychological triggers
• Lifestyle modifications, including sleep optimization and exercise recommendations

Natural and holistic relief approaches

Some natural options for relieving the itching, burning, or irritation associated with hives or rashes include the following.

• Cool it down. A cold compress, or cool shower or bath can help reduce hive-related swelling and the inflammation that drives itching or irritation of most rashes.
• Take an oatmeal bath. Add a colloidal oatmeal product to your bath, or grind the oatmeal in your pantry into a powder and add it to your soak. Oatmeal combats inflammation and relieves itching and irritation.
• Reduce stress. If stress is a trigger for your hives or another type of rash, engage in stress management techniques regularly.
• Consider your nutrition. An anti-inflammatory diet may be of benefit to help keep skin conditions in check, especially those related to autoimmune conditions or autoimmunity.

Key takeaways

• Hives are just one type of rash, but many other rashes can also appear on your skin.
• Hives are distinct because they appear as raised welts; other types of rashes have a different appearance, depending on the cause.
• Working with a knowledgeable care team, such as the folks at Parsley Health can help you get to the root cause of any skin changes. Reach out for a free consultation.

FAQ

How to tell if it’s a rash or hives?

Hives are a type of rash. You can tell if you have hives based on how your skin looks. Hives appear as raised wheals or welts and look a bit like water beading on a sealed hardwood floor or deck. Other types of rashes will look different from each other and different from hives.

What triggers hives?

Allergic reactions, autoimmune conditions, stress, and more are all triggers for hives.

Should you take Benadryl for hives?

Benadryl (diphenhydramine) is an over-the-counter antihistamine used to treat hives and other allergic reactions. However, if you are older or have any underlying conditions or take medications, you should consult your healthcare provider before using Benadryl.

How do you confirm hives?

To confirm whether your skin changes are hives or another type of rash, you should consult a knowledgeable clinician.

How to cure hives fast?

Antihistamines, either oral or topical, are first-line treatment for hives. However, cold compresses and colloidal oatmeal baths are other options that will help soothe your skin.