Chronic idiopathic urticaria is often triggered by physical changes, such as exposure to certain allergens or developing an infection. For some, triggers are mental or psychological, like stress and anxiety.

Idiopathic urticaria is the medical term for hives that seem to have no direct cause. Chronic idiopathic urticaria (CIU) occurs when hives last 6 weeks or more. CIU is also called chronic spontaneous urticaria (CSU).

CIU typically results in itchy, red bumps or “wheals” on the skin. People with CIU usually have flare-ups that come and go for several years and can appear spontaneously.

While current research suggests CIU may be caused by autoimmune dysfunction, the true underlying cause is still not understood.

However, if you’ve been diagnosed with CIU, you may notice that certain triggers can bring about a flare-up or make your symptoms worse.

Here are some of the lesser-known triggers to look out for.

Mental and emotional stress can trigger CIU for some people. It’s also possible that the constant itch and uncomfortable feelings associated with CIU hives can cause more stress, which may make symptoms last longer.

As with many chronic diseases, your mental state plays an important role in the severity of your CIU symptoms. Trying to keep your stress levels in check is an important management technique.

If you find yourself often feeling anxious or overwhelmed, try some stress-relieving activities like:

If those techniques don’t help, consider talking with a healthcare professional about other anxiety-relieving options.

Although scratching itchy skin offers short-term satisfaction, it may actually further trigger symptoms.

Scratching can lead to a vicious cycle in which you become more aware of the itch and cannot stop focusing on it.

The stress caused by this kind of focus can actually lower the itch threshold, meaning the itch seems to become more intense.

Pet dander is a common trigger for occasional hives. If you spend a lot of time around certain animals, they may be triggering your chronic hives.

You don’t necessarily need to make direct contact with an animal to react. Flakes of skin can be shed in places where an animal spends time, which could be enough to bring on a reaction.

If you live with animals, clean your clothes and furniture often to help prevent an allergic reaction.

If you’ve never been diagnosed with a pet allergy but your hives aren’t going away, consider talking with a healthcare professional. CIU can appear at almost any age.

Spending time in nature is wonderful, but it can also potentially trigger your CIU. Pollen, insect bites, and the sun’s heat can all lead to itchy bumps on your skin.

On the other hand, the winter cold or cold conditions such as a swimming pool can also trigger a flare-up in some people.

If you notice your body reacting to cold situations, your healthcare professional might decide to administer an ice cube test to see if a reaction occurs. This test often involves setting a bag of ice on your forearm.

If a red welt appears on your skin after lifting the bag, it’s possible you have cold urticaria or hives caused by the cold. These hives can last for months or go away in a week or so.

You may think your runny nose and hives are unrelated, but it’s possible the two are connected.

Your CIU could be triggered by a:

If you’ve recently been diagnosed with an infection and notice welts developing on your skin, talk with a healthcare professional as soon as possible.

Certain medications may produce chronic hives as a side effect.

Medications known to trigger hives include:

  • antibiotics like penicillin and sulfa
  • aspirin
  • ibuprofen

If you take one of these medications every so often without knowing that it’s a personal trigger, it could be causing hives that stick around for months.

If you notice red, itchy welts on your skin after taking a round of antibiotics or over-the-counter pain relievers, talk with your healthcare professional about a possible connection.

Chronic hives triggered by your body’s immune response to certain foods are rare, but they can happen. People living with celiac disease, for example, may experience CIU.

Dietary triggers that may produce hives include:

If your CIU could be triggered by something you ate or drank, a healthcare professional may recommend keeping a food journal. They may also do allergy testing.

Extra pressure on your skin can lead to hives. Anything from a too-tight pair of jeans to an elastic waistband or a tight belt might trigger symptoms.

If you have a history of chronic hives, opt for loose, comfortable clothing that gives your skin room to breathe.

If you’ve been diagnosed with CIU, one of the best ways to understand the specific circumstances that trigger your symptoms is to track them in a journal. Try to note:

  • the dates of onset
  • your symptoms
  • the intensity of your symptoms
  • any unusual activity around the time your symptoms start

Reviewing your notes with a healthcare professional may help you identify patterns.

Treatment for hives varies depending on the type, but can often include:

If you have CIU, talk with your healthcare professional about your options for symptom management.