Hives can occur for many reasons, including exposure to an allergen or a physical trigger, such as pressure from tight clothing. It may also indicate an infection or other underlying health condition.
Hives often appears as a raised, itchy rash. The medical name for hives is “urticaria.” People also call it welts, wheals, or nettle rash.
Hives affects around 20% of people at some time in their lives. The issue can be chronic or acute.
Keep reading to find pictures of hives, the potential causes, symptoms, treatments, and prevention methods.
Sometimes there is no clear reason why hives occur. However, they can develop as a reaction to:
Allergens
Hives can develop when the body reacts to an allergen. When an allergic reaction occurs, the body releases a protein known as 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 have an allergy to. This is known as “contact urticaria.”
If acute hives results from an allergic reaction, the cause may be:
- a medication, such as:
- some antibiotics
- some nonsteroidal anti-inflammatory drugs, such as aspirin
- angiotensin converting enzyme inhibitors, which are drugs for high blood pressure
- nuts, eggs, seafood, or another food allergen
- latex
- kiwi, banana, chestnuts, or mango, in people with a latex allergy
- some plants, including nettles, poison ivy, and poison oak
- additives in some foods, cosmetics, and other products
Physical triggers
A physical trigger other than an allergen can cause hives. Here are some possible triggers:
- sunlight exposure
- scratching or rubbing the skin
- pressure, from a tight belt, for example
- extreme temperatures or changes in temperature
- 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
- UV light from a tanning bed
- water on the skin, in rare cases
- vibration, in rare cases
Underlying health conditions
Some examples of health conditions that
- viral infections, such as flu, the common cold, glandular fever, or hepatitis B
- bacterial infections, such as some urinary tract infections and strep throat
- intestinal parasites, such as Giardia lamblia
- autoimmune hypothyroidism
- autoimmune conditions, such as rheumatoid arthritis, systemic lupus erythematosus, Sjögren’s disease, celiac disease, and type 1 diabetes
- any other condition that causes inflammation of blood vessels
Sometimes, hives can become chronic as a result of these conditions, or other unknown triggers.
The symptoms of hives include:
- raised, itchy bumps on the skin, ranging from the size of a pinprick to several inches across
- bumps that are pink, red, or skin-colored
- bumps that have a pale center when a person presses it
- bumps that come and go quickly, often within
24 hours , although new ones may form
Hives does not always appear as bumps. The lesions may also be:
- tiny spots
- blotches
- thin, raised lines
The time it takes for the lesions to appear depends on the cause.
In someone with contact urticaria, the reaction occurs
In a person 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.
Hives can appear anywhere on the body, such as the:
- legs
- arms
- trunk
- face
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.
The symptoms of papular urticaria are similar to hives in general, but the bumps tend to be small, between 0.2 to 2.0 centimeters across. They may contain fluid and form in clusters.
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, it may cause 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 anaphylaxis.
If a specific object appears to have triggered the reaction, it may be helpful to take a sample to the hospital.
Anaphylaxis: Symptoms and what to do
Anaphylaxis is a severe allergic reaction that can be life threatening. The symptoms develop suddenly and include:
- hives
- swelling of the face or mouth
- wheezing
- fast, shallow breathing
- a fast heart rate
- clammy skin
- anxiety or confusion
- dizziness
- vomiting
- blue or white lips
- fainting or loss of consciousness
If someone has these symptoms:
- Check whether they are carrying an epinephrine pen. If they are, follow the instructions on the side of the pen to use it.
- Dial 911 or the number of the nearest emergency department.
- Lay the person down from a standing position. If they have vomited, turn them onto their side.
- Stay with them until the emergency services arrive.
Some people may need more than one epinephrine injection. If the symptoms do not improve in 5–15 minutes, or they come back, use a second pen if the person has one.
The best approach to treatment depends on the cause and whether the issue is acute or chronic.
Acute urticaria
Acure urticaria is short-term. If the symptoms are mild and occur after exposure to a specific allergen or irritant, home remedies can soothe the itchiness until the rash disappears.
Options that a doctor may recommend
- antihistamines such as cetirizine (Zyrtec) or fexofenadine (Allegra)
- soothing creams to reduce itchiness
- antiseptic creams to prevent a secondary infection
- short-term use of topical steroids
If there are signs of allergy and the person has swelling in their lips, face, or tongue, the doctor may prescribe an epinephrine auto-injector to carry for use in emergencies.
Chronic urticaria
A person with chronic urticaria may need to take antihistamines regularly until their symptoms resolve.
Omalizumab (Xolair) is an injectable drug that
If tests reveal an underlying disease, such as lupus, the doctor will recommend treatment for this.
Tips for reducing hives symptoms include:
- using a soothing lotion or cool compress to ease the itchiness
- wearing loose, light, cotton clothing
- avoiding scratching
- choosing soaps, moisturizers, and other cosmetics for sensitive skin
- avoiding exposure to known triggers
It is important to speak with a healthcare professional before using supplements, as these can trigger adverse reactions. Some supplements and vitamins contain substances that can trigger hives.
Preventing hives
Some tips for preventing hives include:
- keeping a diary to see if any particular triggers cause them
- avoiding those triggers
- taking over-the-counter antihistamines when the pollen count is high, if pollen may be a trigger
- talking to a doctor about whether medications may be responsible
- using meditation and other relaxation techniques to manage stress
- choosing mild or fragrance-free soaps, skin creams, and detergents
Almost any food can cause an allergic reaction. Learn more about foods that commonly cause allergies.
Doctors can diagose hives by performing a physical examination and asking about a person’s symptoms. They will then try to determine if they are acute or chronic.
Acute urticaria
If the hives only occur in certain situations and are short-lived, this suggests acute hives. Doctors may try to find a trigger by asking what they were doing when the hives began. A doctor may also review the medications or supplements a person takes.
If the trigger is unclear, the doctor may ask a person to keep a symptom diary of when the hives appear. Doctors do not usually recommend extensive allergy testing for a single episode of hives.
Chronic urticaria
If the hives persist for more than 6 weeks, a doctor may recommend blood tests and other tests to identify the underlying cause, though pinpointing the cause is not always possible.
Below are answers to some frequently asked questions about hives.
Are hives contagious?
Hives are not contagious. However, if they occur due to an underlying infection, that infection could be contagious.
Can stress cause hives?
Yes, stress can cause hives in some people. The reason for this is that stress causes a release of adrenalin, which can be a trigger for hives.
Managing stress through meditation, exercise, or mental health treatment may help people with chronic hives manage their symptoms.
What is the difference between hives vs. rash?
Hives are a kind of rash. Doctors tell them apart from other types of rash based on the symptoms.
Hives are raised bumps or areas of skin that appear quickly and are itchy. Usually, each bump lasts
Hives, or urticaria, is a kind of rash. It may result from an allergy, an underlying health condition, or other triggers. Acute hives start suddenly and resolve within
If a person knows that something specific triggers their hives, they may be able to avoid it. However, the cause of hives is not always clear.
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, or cold, clammy skin, the person may have a life threatening condition called anaphylaxis, and they require immediate medical care.