Let's Talk About the Causes of Chronic Hives
Your doctor may be baffled over what, exactly, is causing your hives. Researchers suspect an immune system gone haywire might play a role.
Getting to the root of your chronic hives—a.k.a., chronic idiopathic urticaria (CIU), or chronic spontaneous urticaria (CSU), the official medical terms for this condition—may require patience. We know that feels like a huge ask when all you want to do is scratch off your skin! It’s true that this condition might leave you with more questions than answers—but we’re here to tell you everything we know. Read on.
Our Pro Panel
We went to some of the nation’s top CIU experts to bring you the most scientific and up-to-date information possible.
Morgan Rabach, M.D.
Clinical Instructor in the Department of Dermatology
Mount Sinai Hospital
New York City
Purvi Parikh, M.D.
Adult and Pediatric Allergist and Immunologist
NYU Langone Health
New York City
Ronald L. Ragotzy, M.D.
Allergist and Immunologist
Beloit Memorial Hospital
When it comes to CIU it’s possible, if not probable. Still, it’s best to have an allergist run a full series of tests against tree pollen (and foods that grow from trees that produce it) to make sure that you don’t have food allergies.
Since the cause of chronic hives is undetermined, it’s difficult to pinpoint exactly which triggers you may need to avoid. Still, if you have CIU, known triggers such as NSAID medications and extreme temperature changes should be on your “what to avoid” list.
Yes. Some people who are dermatographic—meaning their skin can erupt in hive-looking welts or redness when it is lightly scratched—are more susceptible. Also, people who generally have sensitive skin have a higher risk of CIU.
They could. Any physical stimulation, whether it’s from a topical chemical or ingredient placed on the skin, can make hives worse. Plus, there can be olfactory connections with hives—in other words, various scents can sometimes lead to skin reactions—even without skin contact.
What Are Chronic Hives, Again?
Hives are pale red, sometimes swollen, welts on your skin. They can itch or feel tingly—and sometimes they even sting. Hives, officially called urticaria, are one of the body’s external indicators that a histamine reaction (a type of immune response) is happening inside you.
It’s estimated that 15% to 25% of people will experience a brief breakout of hives at least once in their lives, but for just under 1% of them, the hives return again and again—for weeks, months or, for the unlucky few, even years. (We know—we’re shuddering at the thought, too!) Regular hives, also called acute hives, can wax and wane for hours, days, or sometimes a few weeks. To be diagnosed with chronic hives, however, your doctor will need to confirm that new hives appear on your skin on most days for six weeks or more.
What Causes Chronic Hives?
The short and totally frustrating answer? No one knows for sure, not even the experts who study this stuff. Why? Because idiopathic—the “I” in CIU—means “no clear cause.”
We get it—that’s probably not what you want to hear right now if you’re struggling with swollen, itchy skin! Here’s what we do know: Regular, run-of-the-mill, acute hives can be caused by any number of factors, including:
The tricky thing about chronic hives, then, is that any or all of the above can possibly trigger an attack—and, yet, for many people with this condition, there is no provable culprit. With so many potential triggers, what causes any particular case of CIU is usually a mystery—which can be trying for both doctors and the people with CIU they treat. We say “usually” because occasionally an allergist can determine that a specific allergen is likely triggering them, but usually the cause remains a big, fat question mark.
Still, there’s another school of thought on CIU, and it’s gaining traction among researchers. Chronic hives may be an autoimmune response gone haywire. This occurs when, for no known reason, the body attacks itself, mistaking its own healthy tissue for a foreign invader or pathogen—like an infection or an allergen—even when no such invader is present.
In the case of chronic hives, the mast cells in the skin get some mixed messages, and they start churning out histamine. This compound can increase blood flow to the skin, drive inflammation, and make you itch like crazy. The result? Those irritating welts, which can even show up on the tongue or in the throat. (And P.S.: If they do appear on the tongue and/or throat and you’re having any trouble breathing, it’s time to get to the ER, pronto.)
Recent studies suggest that 30% to 40% of all chronic hives cases may be autoimmune-related. For example, research shows a connection between CIU and autoimmune thyroid disease. When tested, 22.5% of people with CIU had thyroid autoantibodies present in their systems.
Other studies estimate that as many as 10% to 50% of people with CIU have Hashimoto’s thyroiditis, an underactive thyroid disorder characterized by low energy levels, weight gain, and depression. And still other research shows an increased risk of an overactive thyroid disorder called Graves' disease, caused by a different antibody.
People with CIU also have increased risk for other autoimmune disorders including:
If you suspect an autoimmune disorder may be the at the root of your chronic hives, talk to your doctor, who may instruct you to consult with a rheumatologist (a physician who specializes in rheumatism and arthritis, plus disorders of the joints, muscles, and ligaments).
What Are Common Triggers for Chronic Hives?
Even if you don't have any other autoimmune conditions, there are certain things that can trigger an over-the-top immune response that leads to CIU. They include:
Bacterial or viral, infections may play a significant role in triggering chronic hives. We’re talking things like:
Urinary tract infection
Upper respiratory tract infections
Norovirus and hepatitis C (both of which are caused by viruses)
That’s because infections of all types can trigger a histamine reaction, which may lead to CIU. What is supposed to happen when you have an infection is that your body sends out a signal to produce histamine, which helps you fight off the bad bacteria or virulent virus that's behind the infection.
This signal alerts the immune system that some kind of cell damage is going on. The problem for people with CIU is that instead of just fighting off the infection, histamine production goes into overdrive. Your internal defense system starts attacking healthy cells, too—leading to a weeks’ or even months’-long attack of chronic hives.
For the few cases of chronic hives that are caused by allergens, an allergy test, administered by a specialist, is the best way to understand exactly which ones are causing you to react (or, in this case, overreact). The test is relatively quick (anywhere from 15 to 30 minutes) and consists of the doctor putting a micro-dose of an allergen onto a small patch of skin (usually on your back or on a single arm) and then making a small scratch on the same area. If swelling or redness occurs after a few minutes, the test for that particular allergen is considered positive.
Remember, not all triggers are amenable to testing, but the most common environmental allergens that can cause CIU include:
Some medications (read on for more details on meds)
Scents in the air or against your skin, called olfactory allergic reactions, can also trigger hives. If you’re prone to CIU, be mindful to avoid fragrances and perfumes in your soaps and lotions, as well as fabric softeners.
Close to 11% of U.S. adults have some type of food allergy, according to a 2019 study published in JAMA Open Network. (Again, if you suspect you’re among them, consult with an allergist or immunologist for comprehensive food allergy testing.) These are commonly triggered by:
Raw or uncooked foods: Fresh fruits and vegetables can sometimes trigger hives, while, weirdly, the cooked versions of these same foods aren’t always a problem. Why? Because a reaction can occur from being exposed to certain proteins and other chemicals that are present on raw food, but which are destroyed by heat and the cooking process. Any hives that come from consuming raw fruits or vegetables are usually a result of an allergy to tree pollen.
Additives and/or artificial preservatives: Even if it’s something you eat all the time, a food that has additives or preservatives can bring on a reaction. According to the American Academy of Allergy, Asthma & Immunology, such food allergies to common sulfites (used to reduce browning and spoilage of certain foods) and dyes (mainly red and yellow) are rare but can cause anaphylactic reactions in some people, including the appearance of hives.
Gluten intolerance: Other studies support the notion that a sensitivity to gluten (including wheat, couscous, and spelt), has a direct connection with increased bouts of chronic hives, even if you don't have full-blown celiac disease.
Alcohol intolerance: When your body reacts with flushed skin and hives after drinking, this is called alcohol intolerance. It’s caused by a genetic condition where the body can’t break down alcohol properly. While not considered to be a true food allergy, there may be something in the alcohol that’s triggering you. Maybe it’s the grains, preservatives, or chemicals—who knows? If this describes you, it may be time to consider going zero-proof.
Certain drugs are more likely to trigger an overactive histamine reaction than others in people with CIU. They include:
Non-steroidal anti-inflammatory drugs (NSAIDs): If you have CIU, your first thought might be to grab an over-the-counter pain reliever to help relieve the swelling from so many welts. Not so fast! Some could make your outbreak worse. NSAIDs such as aspirin and ibuprofen can trigger hives as well as wheezing and trouble breathing. The reaction usually occurs within 1 to 6 hours of taking the medication and can be dangerous, so seek immediate medical attention if this happens to you.
Antibiotics: These drugs, especially penicillin and sulfa, are also known to sometimes trigger hives. If you get hives while on a course of antibiotics, contact your physician immediately. If you experience swelling on or near the tongue or throat, or experience any trouble breathing, seek urgent medical care.
Hives can also be triggered by high blood pressure meds (like ACE inhibitors), as well as painkillers (including codeine).
Recent studies have shown that people with autoimmune conditions are more likely to have low B12 levels. The CIU and autoimmune connection suggests that if you have chronic hives, you may want to keep watch on your B12 levels to avoid other conditions like joint pain, anemia, memory loss, and—in more severe cases—losing your sense of taste and smell. Foods rich in B12 include beef, eggs, salmon, sardines, clams, fortified cereal, tuna, nutritional yeast, trout, and milk and dairy products. (So, eat more of ‘em!)
When a woman’s hormones are swinging high and low, hives can be triggered due to imbalances of progesterone and estrogen, which can affect the immune system. (Autoimmune diseases—like thyroiditis, celiac disease, and lupus—can also cause hormonal imbalances.) Talk to your doctor if your hives seem related to your menstrual cycle, menopause, or pregnancy.
Increased Blood Flow
Increased blood flow can potentially lead to temporary inflammation and a histamine release. This can occur from:
Excessive sweating: Hardcore workouts raise your body temperature and increase blood flow—potentially triggering a histamine reaction and the appearance of hives.
Sex: Sex increases blood flow, raising your risk for hives if you are prone to getting them. In addition, if you have an undiagnosed latex allergy, sex with a condom can make things worse. Consider using non-latex condoms.
Extreme Heat or Cold
Piping hot baths are a known hives trigger. In fact, big changes in heat OR cold can do this. If you have CIU, be aware of this and take precautions. Avoid blisteringly hot showers, and bundle up appropriately on super chilly days.
Sensitive Skin or Dermatographia
Somewhere between 2% and 5% of the population has a condition called dermatographia, called “skin writing”—you know, when you can leave an impression on the skin by writing or drawing on it with your finger. This condition is not dangerous, but it can lead to hive-like welts.
According to the American College of Allergy, Asthma and Immunology (ACAAI), tight or restrictive clothing can trigger or worsen a CIU outbreak. Choose breathable and/or soft fabrics, skip skintight jeans, and avoid itch-inducing laces and wools, elastic belting, or anything that irritates or presses into the skin.
Usually stress does not cause hives on its own, but it can make the underlying condition worse. On a physical level, stress triggers the nervous system, which can lead to scratching, a potential trigger for hives. At the physiological level, anxiety or stress can send your immune system into overdrive, which will then turn your histamine faucet on.
Stress-reducing tactics can help calm the nervous system and hopefully prevent a CIU flare up. Different approaches include:
Guidance from a mental health professional
Now that you know the common triggers for chronic hives—if not always the exact combination of factors that may cause your own—you’re better prepared to prevent your next bout with them. If you notice a reaction after wearing elastic waistbands, for instance, or always seem to get them for six weeks or more in the springtime during peak outdoor allergy season, it makes sense to switch up your wardrobe, or speak to your doctor about medications (like antihistamines) that might help alleviate your symptoms. If you struggle with stress, tell your doctor about that, too. Consider exploring the autoimmune response angle, especially if you have other symptoms of Graves’, lupus, or another autoimmune disorder. And know that with a half-million other people in the U.S. living with CIU, you’re definitely not alone.
- CIU Basics: Mayo Clinic. (n.d.). “Chronic Hives.” mayoclinic.org/diseases-conditions/chronic-hives/symptoms-causes/syc-20352719
- CIU Causes: American Academy of Dermatology. (n.d.). “CIU: Who Gets and Causes.” aad.org/public/diseases/a-z/hives-causes
- CIU and Autoimmune Response (1): Frontiers in Immunology. (2019.) “Autoimmune Theories of Chronic Spontaneous Urticaria.” frontiersin.org/articles/10.3389/fimmu.2019.00627/full
- CIU and Autoimmune Response (2): Indian Journal of Dermatology. (2009.) “Chronic Idiopathic Urticaria: Where Do We Stand?” ncbi.nlm.nih.gov/pmc/articles/PMC2810697/
- CIU And Graves’ Disease: AD Annuls of Dermatology. (2016). “Effect of Levothyroxine Treatment on Clinical Symptoms in Hypothyroid Patients with Chronic Urticaria and Thyroid Autoimmunity.” ncbi.nlm.nih.gov/pmc/articles/PMC4828383/
- CIU and Celiac Disease: European Journal of Dermatology. (2014). “Does urticaria risk increase in patients with celiac disease? A large population-based cohort study.” ncbi.nlm.nih.gov/pmc/articles/PMC3896876/
- CIU and Food Allergies: JAMA Open Network. (2019). “Prevalence and Severity of Food Allergies Among US Adults.” ncbi.nlm.nih.gov/pmc/articles/PMC6324316/
- CIU and B12 Deficiencies: BioMed Research International. (2015). “Association between Micronutrient Levels and Chronic Spontaneous Urticaria.” ncbi.nlm.nih.gov/pubmed/15736714