Food allergies can affect your skin in a number of ways. For example, you may develop a rash that resembles eczema or hives and bruising that can last for days.

“I’ve had testing done, and the doctor has narrowed my allergies down to certain foods,” one MyFoodAllergyTeam member wrote. “My breakouts can be from the size of a dime to double the size of my hand. It’s a raised rash that has the touch of heat and itches and swells — sometimes it looks like it leaves a bruise when it starts going away.”

If you’ve had hives and bruises that appear together, it’s important to know what may be causing them. Check out a few potential issues that could lead to hives and bruising, along with steps to take if you experience these symptoms.

Food Allergies and Hives or Bruising

Also called urticaria, hives are relatively common, affecting about 1 in 5 people at some point. These itchy bumps may be discolored or the same color as your natural skin tone.

Hives are a common symptom of food allergies. More than 5,400 MyFoodAllergyTeam members say they’ve experienced hives.

Bruising isn’t typical among people with food allergies but can happen if you’re unable to absorb nutrients properly. This is called malabsorption.

Malabsorption may occur among people with celiac disease. This condition isn’t a food allergy or food intolerance but is, instead, an autoimmune condition triggered by consuming gluten, a protein found in many grains. Over time, celiac disease causes intestinal lining damage that makes it hard for the body to absorb nutrients.

If you become malnourished due to celiac disease, you may bruise more easily. Celiac disease can also cause a rash and itchy skin. For this reason, some people may think they have hives and bruising triggered by an allergen, when in actuality they’re experiencing symptoms of celiac disease.

Other Causes of Hives and Bruising

In most cases, food allergies aren’t likely to result in both hives and bruising. Other potential causes of these simultaneous symptoms include certain conditions involving blood vessels or skin.

Urticarial Vasculitis

Vasculitis is a general term that describes damage to blood vessels because of inflammation or swelling. One type, called urticarial vasculitis, causes painful, itchy hives.

The hives usually last longer than 24 hours. When they fade, they may leave behind bruises. Urticarial vasculitis is commonly caused by an autoimmune reaction — your own immune system attacks your blood vessels.

To diagnose this condition, a dermatologist or other specialist may do a skin biopsy. During this procedure, the doctor takes a small tissue sample to check for evidence of disease. If you’re found to have urticarial vasculitis, your provider might prescribe a nonsteroidal anti-inflammatory drug (NSAID), such as ibuprofen or aspirin. They may also recommend medications such as corticosteroids, antihistamines, or immunosuppressants.

Allergic Reactions

Some people may experience a serious allergic reaction called allergic vasculitis. This usually happens in response to medications, infections, or other substances from outside the body. Food allergies aren’t typically the cause. Your health care provider may also refer to it as hypersensitivity vasculitis, cutaneous small vessel vasculitis, or leukocytoclastic vasculitis.

Allergic vasculitis can damage blood vessels in your skin, which may then lead to a variety of symptoms. These include a rash with discolored spots that are tender to the touch, similar to a bruise, as well as hives.

Because this condition is often triggered by an allergic reaction to medication, the treatment is typically to discontinue the drug. Your health care team may also ask you to take corticosteroids or NSAIDs to help reduce the inflammation.

Dermatomyositis

This rare condition causes a rash and muscle inflammation. One possible symptom involves a discolored rash that may resemble a bruise. Dermatomyositis may also cause spots and itching, which some people may mistake for hives and bruising. Other symptoms may include muscle weakness on both sides of the body that gets worse over time.

If your doctor thinks you may have dermatomyositis, they’ll perform a series of tests, such as blood tests, an MRI, biopsies, or an electromyogram (a test that evaluates electrical activity in muscles).

Immune Thrombocytopenic Purpura

Immune thrombocytopenic purpura (ITP) is a blood disorder that affects platelet counts (the number of cells that help blood clot). With this autoimmune condition, the immune system creates antibodies that seek and destroy platelets. This process results in a low platelet count, which means the body can’t properly plug holes in damaged blood vessels.

Researchers aren’t sure what causes ITP. Like other autoimmune disorders, ITP can run in families, but researchers aren’t sure how this happens. A person is at a higher risk of ITP if their parent or sibling has it.

The condition is rare, affecting around 9.5 out of 100,000 people in the U.S. ITP causes excess bleeding, such as nosebleeds, and easy bruising. The bruises can show up at the knee and elbow joints, caused by “leaked” blood. Small blood vessels beneath the skin break, allowing blood to escape and pool under the skin’s surface. The pooled blood appears as a discolored mark. Although hives aren’t commonly associated with ITP, one study found that individuals with hives had an increased risk of developing ITP.

When To Call Your Doctor About Hives and Bruising

In most cases, hives resolve on their own within a day or so and don’t require further testing, but some cases call for more examination. For example, if hives occur alongside bruising, your doctor will want to identify what’s causing the issue.

If you or your child experiences hives along with bruising, bleeding in the skin, discolored lumps, joint soreness, or a high fever, call a doctor right away.

Hives along with difficulty breathing, fainting, dizziness, or a swollen tongue or throat could be a sign of anaphylaxis, a life-threatening allergic reaction. If anaphylaxis is suspected, give emergency medication (such as an epinephrine auto-injector) and call 911 right away.

Talk With Others Who Understand

MyFoodAllergyTeam is the social network for people with food allergies and their loved ones. On MyFoodAllergyTeam, more than 41,000 members come together to ask questions, give advice, and share their stories with others who understand life with allergies to food.

Have you experienced hives and bruising while living with food allergies? How did you handle it? Share your experience in the comments below, or start a conversation by posting on your Activities page.