Is this cause for concern?
Cholinergic urticaria (CU) is a type of hives brought on by raised body temperature. It typically develops when you exercise or sweat. More often than not, CU appears and disappears on its own within a few hours.
In severe cases, CU can sometimes be related to exercise-induced anaphylaxis. Seek immediate medical attention if this is the case. If you have an epinephrine injector (EpiPen), administer your medication while you wait for help to arrive.
Picture of cholinergic urticaria
If you’re experiencing CU, you may have:
- wheals (small, raised bumps on the skin)
- redness around the bumps
These bumps typically develop within the first six minutes of exercise. Your symptoms may worsen for the next 12 to 25 minutes.
Although wheals can appear on your body, they often begin on your chest and neck first. They may then spread out to other areas. These bumps can last anywhere from a few minutes to about four hours after exercise.
You may also experience symptoms unrelated to your skin’s surface. These include:
- abdominal pain
CU can also be accompanied by exercise-induced anaphylaxis, a more severe allergic reaction to exercise. Its symptoms can be life-threatening and require immediate medical attention. Call 911 if you experience:
- difficulty breathing
- abdominal pain
If you have an EpiPen, you should administer the medication while you wait for help to arrive.
What causes CU and who is at risk
CU occurs when your body temperature rises. This can happen for a number of reasons, such as:
- participating in sports
- taking a hot bath or shower
- being in a warm room
- eating spicy foods
- having a fever
- being upset or angry
- experiencing anxiety
Whatever activity or emotion raises your body’s temperature also triggers your body to release histamine. This is what causes the symptoms of CU to appear.
Anyone can develop CU, but men are most likely to be affected. CU generally begins around age 16 and may continue until age 30. You may be more susceptible to CU if you experience other forms of hives or have another skin condition.
How it’s diagnosed
If your symptoms aren’t severe but interfere with your lifestyle, see your doctor. A simple evaluation and conversation about your symptoms may be enough for them to diagnose CU.
In some cases, your doctor may want to conduct tests to gather more information about the condition. These may include:
- A passive warming test: This will raise your body temperature with warm water or an increased room temperature. Your doctor can observe your body’s reaction when exposed to increased heat.
- A methacholine skin challenge test: Your doctor will inject methacholine into your body and observe for a reaction.
- An exercise challenge test: Your doctor will have you exercise and watch for symptoms of CU. You may also be measured with other medical instruments during the test.
You should see a doctor immediately if you suspect you have exercise-induced anaphylaxis, which must be attended to as soon as symptoms occur.
Your doctor will work with you on a treatment plan that’s suited to your individual needs.
If your symptoms are mild, simple lifestyle changes may be all you need. However, lifestyle modifications can be difficult to adhere to if you’re an athlete or if you engage in physical or strenuous activity in your daily life. Medication may be a better option for some.
One of the simplest ways to manage CU is to modify the way you exercise and to avoid situations that raise your body temperature. Your doctor can advise you on how to best achieve this. Depending on your needs, treatment may involve limiting outdoor exercise during the summer months and learning strategies to manage stress and anxiety.
Antihistamines are the first line of medication your doctor may try to prevent and treat CU. These may include H1 antagonists, such as hydroxyzine (Vistaril) or terfenadine (Seldane), or H2 antagonists, such as cimetidine (Tagamet) or ranitidine (Zantac).
You may also be prescribed a medication to control the amount you sweat, such as methantheline bromide or montelukast (Singulair). Your doctor may also recommend beta blockers, immunosuppressants, or even UV light to treat CU.
If you experience exercise-induced anaphylaxis, your doctor will prescribe an EpiPen to use if symptoms appear. Talk to them about how to use the EpiPen so that you’re prepared if severe symptoms occur. You may also want to have an exercise partner nearby so that they can step in and administer the medication if needed.
CU symptoms generally disappear in a matter of hours. If you frequently have the symptoms, you may want to talk to your doctor about how to prevent future episodes.
You should always seek immediate medical care if the condition causes wheezing, difficulty breathing, or other serious symptoms.