Hives (Urticaria) Overview

Hives also known as urticaria, is a skin reaction that causes itchy welts. Chronic hives are welts that last for more than six weeks and return often over months or years. Often, the cause of chronic hives isn’t clear.

The welts often start as itchy patches that turn into swollen welts that vary in size. These welts appear and fade at random as the reaction runs its course. Chronic hives can be very uncomfortable and interfere with sleep and daily activities. For many people, anti-itch medications (antihistamines) provide relief.

Hives are usually appear as raised itchy rash. These are red, pink, or flesh-colored, and sometimes they sting or hurt. In most cases, hives are caused by an allergic reaction to a medication or food or a reaction to an irritant in the environment.

Hives affects around 20% of people at some time in their lives. The issue can be chronic or acute. Acute hives lasts 6 weeks or less, and it may result from exposure to an allergen or irritant, such as a food or touching a nettle.

Chronic urticaria is a long-term disease. Doctors do not know exactly why it happens, but it may accompany a chronic health condition or an autoimmune condition. A patient with chronic urticaria may have hives every day for months or years.

It is not possible to catch hives from another person. However, in some cases, hives occurs with a contagious infection.

If a person has hives, they have a risk of developing a life threatening condition called anaphylaxis. Being aware of other symptoms of this condition, such as swelling of the face, tongue, or throat, a rapid heartbeat, or lightheadedness is important. Anyone who might have anaphylaxis should receive urgent medical care.

Causes of Hives

Hives are usually caused by an allergic reaction to something that you have encountered or swallowed.

When you have an allergic reaction, your body begins to release histamines into your blood. Histamines are chemicals your body produces in an attempt to defend itself against infection and other outside intruders.

In some people, the histamines can cause swelling, itching, and many of the symptoms that are experienced with hives. In terms of allergens, hives can be caused by factors such as pollen, medications, food, animal dander, and insect bites.

Hives might also be caused by circumstances besides allergies. It’s not uncommon for people to experience hives as the result of stress, tight clothes, exercise, illnesses, or infections.

It’s also possible to develop hives as the result of excessive exposure to hot or cold temperatures or from irritation due to excessive sweating. As there are several potential triggers, many times the actual cause of hives cannot be determined.

Hives can develop as a reaction to:

  • An allergen
  • Another physical trigger, such as extreme temperatures
  • An underlying health condition

Sometimes there is no clear reason why they occur. In the case of chronic hives, some experts believe that it may result from an autoimmune reaction, but they are still unsure.

Allergens

Hives can develop when the body reacts to an allergen. When an allergic reaction occurs, the body releases a protein called histamine. Next, tiny blood vessels called capillaries leak fluid. This fluid accumulates in the skin and causes inflammation and a rash. As fluid accumulates under the skin, small bumps form.

The reaction can occur if a person consumes something or touches something that they are allergic to. This is known as “contact urticaria.”

If acute hives results from an allergic reaction, the cause may be:

  • A medication, such as:
    • Angiotensin converting enzyme inhibitors, which are medicines for high blood pressure
    • Certain antibiotics
    • Some non-steroidal anti-inflammatory drugs, or NSAIDs, such as aspirin
  • Additives in some foods, cosmetics, and other productsKiwi, banana, chestnuts, or mango, in people with a latex allergy
  • Latex
  • Nuts, eggs, seafood, or another food allergen
  • Some plants, including nettles, poison ivy, and poison oak


Physical Triggers

A physical factor other than an allergen can cause hives.

Following are some possible triggers:

  • A high body temperature, due to sweating, exercise, anxiety, or a hot shower
  • Adrenalin, which the body releases during exercise and exposure to heat or stress
  • Extreme temperatures or changes in temperature
  • Pressure, from a tight belt, for example
  • Sunlight exposure
  • Scratching or rubbing the skin
  • UV light from a tanning bed
  • Vibration, in rare cases
  • Water on the skin, in rare cases


Underlying Health Conditions

Some examples of health conditions that can cause hives include:

Chronic hives may start as an autoimmune response, but the exact cause is unknown.


Types of Hives

Allergic Reactions

The most common causes of hives are allergic reactions. These can be caused by any allergen you might be sensitive to, including:

  • Dust mites
  • Foods (such as nuts, milk, and eggs)
  • Insect bites or stings
  • Medications (primarily antibiotics, cancer drugs, and ibuprofen)
  • Pet dander
  • Pollen

Mild cases of hives caused by allergies are typically treated with long- or short-term allergy medications and avoidance of the trigger.

Anaphylaxis

Anaphylaxis is a severe, life-threatening allergic reaction. In this condition, hives are often accompanied with breathing difficulties, nausea or vomiting, severe swelling, and dizziness. Call 911 immediately if you suspect anaphylaxis.

Chronic Hives

Chronic hives are ongoing cases that don’t necessarily have an identifiable cause. Also called chronic urticaria, this condition is marked by recurring hives that can interfere with your lifestyle. According to the Mayo Clinic, these can last between six weeks and several months or years.

You may suspect chronic hives if you have welts that don’t go away within six weeks. While not life-threatening, this form of hives can be uncomfortable and difficult to treat. They may also be a symptom of an underlying health problem, such as:


Dermatographism

This form of acute hives is considered mild. Excessive scratching or continuous pressure on the skin causes it. Dermatographism usually clears up on its own in a short period of time without treatment.

Temperature-Induced Hives

Sometimes changes in temperature can induce hives in people who are sensitive to such changes. Cold-induced hives may occur from cold water or air exposure, while body heat from physical activity may cause exercise-induced hives. Exposure to sunlight or tanning beds may also bring about solar hives in some individuals.

Infection-Induced Hives

Both viral and bacterial infections can cause hives. Common bacterial infections causing hives include urinary tract infections and strep throat. Viruses that cause infectious mononucleosis, hepatitis, and colds often cause hives.

Signs and Symptoms of Hives

Hives symptoms can last anywhere from minutes to months, or even years.

Hives often has the following features:

  • Characteristic raised skin lesions can appear in any area of the body.
  • Lesions often appear in batches.
  • These tend to be itchy
  • They may be pink, red, or skin-colored.
  • If a person presses in the middle, the coloring may fade.
  • The bumps usually last no longer than 24 hours, but new ones may form.
  • Their size can range from that of a pinprick to several inches across.

Hives does not always appear as bumps. The lesions may also be:

  • Blotches
  • Thin, raised lines 
  • Tiny spots

The time it takes for the lesions to appear depends on the cause.

In someone with contact urticaria, the skin reacts to an allergen, such as latex or an irritant. The reaction occurs 10–60 minutes after exposure to the allergen and lasts up to 24 hours.

In an individual with a food allergy, hives usually appear within 1 hour. Reactions to food colorings and other additives can appear after 12–24 hours. A reaction to a drug can appear at once or much later, even years after starting to use the medication.

In some cases, hives persists for several days. People with chronic hives can have the symptoms for months or years.

Other symptoms of chronic hives include:

  • Batches of welts (wheals) that can arise anywhere on the body
  • Flares triggered by heat, exercise or stress
  • Welts that might be red, purple or skin-colored, depending on your skin color
  • Itchiness (pruritus), which can be intensez
  • Welts that vary in size, change shape, and appear and fade repeatedly
  • Painful swelling (angioedema) around the eyes, cheeks or lips
  • Symptoms that persist for more than six weeks and recur often and anytime, sometimes for months or years

Hives on Different Parts of the Body

Hives can appear anywhere on the body, such as the:

  • Arms
  • Face
  • Legs
  • Trunk

Hives on the legs

Some people have “papular urticaria” in reaction to insect or spider bites. It usually affects children who have not yet developed immunity to these bites. The lesions can develop anywhere, but commonly occur on the legs.

Below are some typical features:

  • The characteristic itchy red bumps, known as papules, form in clusters.
  • Each papule measures 0.2 to 2.0 centimeters across and has a central point.
  • They may be fluid-filled.
  • New papules may appear as old ones disappear.
  • A new insect bite may cause papules to reappear.


Hives on the Face

When hives results from an allergy or sensitivity reaction, it can significantly affect the face, for example, by causing swelling in the lips.

The swelling can become more widespread and affect the mouth, throat, and airways. In this case, the person may find it hard to breathe. This is an emergency, and the person needs urgent medical care. They are at risk of developing a life threatening condition called anaphylaxis.

If the person has an autoinjector, start by helping them use it. Then, call 911, or the local emergency number, and stay with the person until help comes. If a specific object appears to have triggered the reaction, it may be helpful to take a sample to the hospital.

Diagnosis Of Hives

To diagnose hives a doctor first needs to determine whether the issue is acute or chronic.

Acute Urticaria

First, the doctor, who may be a dermatologist, examines the affected areas. Next, they try to identify the trigger.

They often ask:

  • About exposure to likely triggers, such as latex gloves, chemicals, or an insect bite
  • When and where the rash began
  • About any current medications, including herbal supplements
  • Whether there is any family history of hives
  • About the person’s medical history

Often, the trigger is unclear. If there is a likely trigger, the doctor might refer the person to an allergy clinic. If they suspect a food allergy, they may suggest keeping a food diary.

At an allergy clinic, a specialist may do a skin prick test to find out whether there is an allergy to specific substances, such as chemicals, dust mites, or specific foods.

However, a doctor does not usually recommend extensive allergy testing for a single episode of hives.

Chronic Urticaria

Most cases of hives resolve after 6 weeks, but around 8% persist for longer. This is chronic urticaria. A doctor may recommend blood tests and other tests to identify the underlying cause, though pinpointing the cause is not always possible.

Chronic urticaria is unlikely to result from an allergy or contact with an irritant, so doctor will probably not recommend a skin prick test.


Treatment of Hives

Treatment for chronic hives often starts with nonprescription anti-itch drugs (antihistamines). If these don’t help, your health care provider might suggest that you try one or more of these treatments:

Prescription Anti-Itch Drugs: The usual treatment for chronic hives is prescription antihistamine pills that don’t make you drowsy. These drugs ease itching, swelling and other allergy symptoms. Daily use of these drugs helps block the symptom-producing release of histamine. Examples include:

  • Cetirizine
  • Desloratadine (Clarinex)
  • Fexofenadine

These medications have few side effects. If the non-drowsy antihistamines don’t help you, your doctor may increase the dose or add another type of antihistamine.

Check with your doctor before taking any of these medications if you’re pregnant or breastfeeding, have a long-term medical condition, or take other medications.

Other Medications

If the first-choice drugs don’t ease your symptoms, other drugs may help. For example:

  • Cimetidine (Tagamet HB)
  • Doxepin (Silenor, Zonalon)
  • Famotidine (Pepcid AC)
  • Montelukast (Singulair)
  • Nizatidine (Axid AR)
  • Omalizumab (Xolair)
  • Ranitidine (Zantac)

For chronic hives that resist these treatments, your doctor might prescribe a drug that can calm an overactive immune system. Examples are cyclosporine (Gengraf, Neoral, Sandimmune), tacrolimus (Prograf, Protopic, others), hydroxychloroquine (Plaquenil) and mycophenolate (Cellcept, Myfortic).

Lifestyle Changes and Home Remedies

Chronic hives can go on for months and years. They can interfere with sleep, work and other activities. The following self-care tips may help you manage your condition:

  • Avoid triggers. These can include foods, medications, pollen, pet dander, latex and insect stings. If you think a medication caused your welts, stop using it and contact your primary care provider. Some studies suggest that stress or fatigue can trigger hives.
  • Use a nonprescription anti-itch drug. A nonprescription anti-itch (antihistamine) pill that doesn’t cause drowsiness may help ease itching. Examples include loratadine (Alavert, Claritin, others) and cetirizine (Zyrtec Allergy).
  • Apply cold. Soothe the skin by covering the itchy area with a cold washcloth or rubbing an ice cube over it for a few minutes.
  • Take a comfortably cool shower or bath. Some people might relieve itching in the short term by taking a cool shower or bath. Try sprinkling the bath water with baking soda or oatmeal powder (Aveeno, others).
  • Apply an anti-itch cream or lotion. Try a cream with menthol for a soothing effect.
  • Wear loose, smooth-textured cotton clothing. Avoid wearing clothing that’s rough, tight, scratchy or made from wool.
  • Protect your skin from the sun. Liberally apply sunscreen about a half hour before going outdoors. When outdoors, seek shade to help relieve discomfort.
  • Track your symptoms. Keep a diary of when and where hives occur, what you were doing, what you were eating, and so on. This may help you and your health care provider identify triggers.


Complications of Hives

Chronic hives don’t put you at sudden risk of a serious allergic reaction (anaphylaxis). If you do get hives as part of a severe allergic reaction, seek emergency care. Symptoms of anaphylaxis include dizziness, trouble breathing, and swelling of the tongue, lips, mouth or throat.

Prevention of Hives

To lower your likelihood of experiencing hives or angioedema, take the following precautions:

  • Avoid known triggers. If you know what has triggered your hives, try to avoid that substance.
  • Bathe and change your clothes. If pollen or animal contact has triggered your hives in the past, take a bath or shower and change your clothes if you’re exposed to pollen or animals.

Tips for preventing hives may include:

  • Choosing mild or fragrance-free soaps, skin creams, and detergents
  • Taking over-the-counter antihistamines when the pollen count is high, if pollen may be a trigger
  • Keeping a record of any possible triggers, such as a food diary
  • Talking to a doctor about whether medications may be responsible
  • Using meditation and other relaxation techniques to manage stress

Almost any food can cause an allergic reaction. Some common triggers include:

  • Eggs
  • Milk
  • Nuts
  • Sesame
  • Soy
  • Seafood 
  • Wheat

Keeping a record of meals and symptoms can help identify which foods are triggering the reaction.


Hives and Stress

One trigger for acute hives may be adrenalin, the American Academy of Dermatology explains.

Research has linked persistent stress with a mild underlying infection in people with chronic urticaria, and experts are interested in finding out whether these issues have a shared underlying mechanism.

Managing stress through meditation, exercise, or counseling may help some people with chronic hives manage their symptoms.

Summary

Hives, or urticaria, is a kind of rash. It may result from an allergy, another trigger such as adrenalin, an underlying health condition, or other factors. Acute hives starts suddenly and resolves within 6 weeks, while chronic hives can last for months or years.

If an individual knows that something specific, such as seafood, triggers hives, they may be able to avoid it. However, the cause of hives is not always clear, so prevention is not always possible.

If hives is affecting the quality of life, speak with a doctor. They can recommend treatment and check whether an underlying health issue is the cause.

If hives occurs with swelling in the mouth or throat, nausea, faintness, a rapid heartbeat (tachycardia), or cold, clammy skin, the person may have a life threatening condition called anaphylaxis, and they require immediate medical care.

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