Hives

In this article:

• What are hives (urticaria)?
• Symptoms
• When to see a doctor
• Causes
• Different types of hives
• Ordinary hives
• Risk factors and causes of ordinary hives
• Chronic hives
• Important
• What do hives look like?
• Complications
• References

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What are hives (urticaria)?

Hives is the common name for the urticaria – an itchy rash that migrates. Hives is not specific for any particular disease, and can be a symptom of a hidden health condition. This type of rash can look differently, from single mosquito-bite type of single lesions popping up on any part of the body to large areas of puffiness and redness.

There are couple of sings that identify hives:

• Itch. It can come even before the hive, and if you scratch the skin, the actual hive may appear. Itching can be so bothersome it disrupts sleep and usual activities
• Dermatographia. This is the condition when a red strip with white clearing in the middle will appear on the skin when you scratch it. In translation from Latin, it actually means “writing on the skin”
• Hives do not leave scars. Not unless you scratch yourself too hard
• Most hives migrate. The rash can appear on one part of the body, then disappear, then come on again on in a different location

Urticaria is annoying and disrupting, but not deadly on its own. In a way, it is a body’s red flag that something is not right. If you develop hives, it is a good idea to see an allergist or an immunologist. Usually, many tests are necessary to diagnose the reason for hives. 

Hives do come with angioedema – a swelling of the mucus membranes and skin. This can be dangerous because if it happens to the throat, the angioedema can block the air entry into the lungs. This condition can cause lots of anxiety and fear. Certain blood test and genetic tests can help to identify a condition caused hereditary angioedema. This is rare, and does run in families.

Urticaria can be a sign of a food or environmental allergy. This is an emergency, as other signs of a systemic allergic reaction (swelling, difficulty breathing, fainting etc.) will appear leading to anaphylaxis. Epinephrine is the only life-saving medication when given as a self-injector. As food allergies are on the rise, hives become more common than ever.

Symptoms

Here are the common symptoms of hives:

1. Itching and sometimes painful to touch skin
2. Swollen bump of different shape surrounded by redness
3. No signs of infection
4. Some hives merge together

When to see a doctor

Most of the time, if the hives do not resolve, you want to see a doctor. If hives appear with other worrisome signs, such as difficulty breathing and swelling of the throat, you need to go to the emergency room or call emergency number right away.

Here is couple or reasons to see a doctor with hives:

1. Itch is so intense it interferes with daily activity and sleep
2. Hives continue for longer than 3 days or come back after resolving
3. Swelling of mucus membranes and face with hives
4. There are other systemic issues that happen when hives appear (fast heart rate, sweating, vomiting, difficulty breathing, wheezing etc.)

The usual doctor to start with is a primary care practitioner (or emergency physician if hives come with scary life-threatening signs). The specialist who diagnoses hives and most likely will find the reason for them is an Allergist-Immunologist

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Causes

There are still debates on exact mechanism of the urticaria. We know for sure that mast cells (allergy-related cells) and nerve endings are involved. It is clear that hives that happen as a result of allergic reaction are formed by the active factors released by the mast cells. Histamine produces intense itch and forms the welt (puffy swelling). But how hives can happen after viral infection and stress – we don’t really know.

Diagnosis of hives is easy, but finding the reason is not. You are lucky if you are able to connect hives with certain event that trigger them consistently. For example, hives happen every time a cat licks you. Here are few common hives triggers:

• Allergies. Cats, grass pollen and food are known well to generate hives
• Infections. Some viral infections are notorious in causing hives even weeks after recovery: CMV, Epstein-Barr virus, adenovirus and even COVID-19 are good examples
• Stress. It is known that in some individuals severe acute stress can start up urticaria
• Benign childhood urticaria. That happens when the baby starts teething or eating new foods. It goes away on its own as the baby grows out of it.
• Sun and extreme cold. some people have hives just because of sun of cold exposure
• Autoimmune disease. for example, hives can start due to thyroid inflammation or liver disease
• Medications. Urticaria is one of the most common side effects or allergic reaction to drugs
• Biological medications. For example allergy shots could cause urticaria, or biological injections such as omalizumab
• Body fluids. Yes, no matter how bazaar it sounds, people can have hives to saliva, sweat and semen fluid getting in contact with skin
• Unknown (idiopathic urticaria). This is the type when doctors just cannot find the cause

There is also a difference between the definition of the factors that caused hives in the first place and factors that trigger a new bout of urticaria. Here are triggers that will bring up symptoms in people who suffer from hives:

• Mechanical triggers: pressure like wrist bands or belts, pushing your elbow against the table, carrying a purse on a forearm, wearing a hat
• Temperature. A change of temperature from hot to cold and in reverse can bring up hives. Example – jumping in a cold pool, taking a hot shower
• Scratching. Sometimes the hives will start if you just itch a part of your body
• Emotions. Even if the hives are not caused by the stress, getting angry or upset can start the rash

Some scientists and doctors actually divide hives into spontaneous (coming up on its own) and inducible or physical urticaria. This makes it even more confusing. This means that hives come and go it their own – it is the first type. But if your hives come up only with some trigger factor – it is inducible. It does not really make it easier for you, but the doctor might do some special tests if you have hives only in a certain environment, like exposed to cold.

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Different types of hives

As we already discussed, hives is more a symptom that can follow or precede some diseases or conditions. So, in order to organize these disorders, doctors came up with classifications.

Ordinary hives

While the name of this urticaria sounds totally benign, it does not mean this is a better type. Even worse – once you had hives your body “learns” to make them! What that means is you can have them again and again for different reasons in your life. Some people get so used to hives, they start just “living with hives”. That is why many allergists believe that hives must be treated aggressively and as fast as possible.

Risk factors and causes of ordinary hives

One of the most common causes of the hives is allergy. While sneezing and just caving runny nose is a local allergy that can be managed easily, do not delay seeing an allergist if you or your child got hives with that. That means that it is now a systemic problem that affects the whole immune system. The same it true for the autoimmune disease. your body is trying to signal you – go to the specialist!

Chronic hives

If you have the hives for longer than about 6 month – it is called chronic hives. That means whatever causes them is still present in the body, or in contact with the body. This is one of the most annoying types of hives, as you never know why and how the new bout of hives will start. Most people end up on chronic medications and even use biological injections that just stop the body from producing hives.

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Important

1. Hives is not a disease. this rash is a “red flag” that something is not right in the body
2. If hives do not have any other symptoms, it is most likely triggered by a virus that “messed up with immune system”. In this case, the virus is most likely gone but left hives as a trace.
3. Dermatographia is not hives, but is a skin condition when just a simple point pressure or a scratch cause long-standing red streak
4. Hives most commonly get confused with insect bites (like fleas)
5. All hives deserve investigation. A good start is a primary care office.

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What do hives look like?

Hives are very different in shapes and sizes. Most commonly they look like a bite of the insect. The only difference – you cannot find the central puncture. If many of them arrived at the same spot they can merge together to form a huge swelling in the middle with redness that spreads around. Some hives happen in a line wile others create circles.

They can have almost perfect round shape or a weird landscape design. Hives that are triggered by cold or sun will stay on the parts of the body that was not covered with the clothes. Urticaria that is caused by pressure may follow the line of your belt or stay in the place where your purse handles touched the forearm.

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Complications

Hives do not cause complications. But it is important to get the right diagnosis and find the actual reason, because hives are the red flag of many systemic diseases. It you find out about a thyroiditis or a food allergy on time, you can get rid of the hives and prevent complications of a significant disease.

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References

Chronic Spontaneous Urticaria: The Devil’s Itch. Saini SS, Kaplan AP.J Allergy Clin Immunol Pract. 2018 Jul-Aug;6(4):1097-1106. doi: 10.1016/j.jaip.2018.04.013.PMID: 30033911 Free PMC article. Review.