What Does an Allergic Reaction Bump Look Like?

Medically Reviewed on 10/27/2022
Allergic Reaction Bump
Hives are caused as a result of the body’s response to any allergens.

Hives or urticaria are allergic reaction bumps or welts that appear reddish, itchy, or raised. When pressed gently, blanching (turns into pale color) can be noticed.

What are hives?

Hives are also called urticaria. About 20 percent of people experience hives at some time in their lifetime.

  • Most hives are sudden and caused by any allergen, such as food, or touching some chemicals, metals, or allergy-causing plants (such as nettle).
  • They could be itchy and cause a burning sensation.
  • The size of the hives may vary from quite tiny bumps to as big as a dinner plate. Small bumps often combine to form larger ones.

Bumps start at one place and disappear and come back at some other place. This condition can be acute (the short duration that is last for six weeks) or chronic (lasts for more than six weeks to several months).

Hives are not contagious and do not cause serious complications. Some triggers for the hives, such as bacterial or viral infection, can be contagious.

What are the causes of hives?

Sometimes, the exact cause may be unknown (idiopathic). The following are the causes of hives or urticaria:


Hives are caused as a result of the body’s response to any allergens. When the allergic reaction takes place, the body releases a chemical called histamine. The capillaries (tiny blood vessels) leak fluid that accumulates in the skin, causing inflammation and rash. The tiny bumps are due to the accumulation of fluid under the skin.

The reaction occurs when a person comes in contact with or eats something they are allergic to, causing allergic reactions.

A few allergens that cause allergic reactions:

  • Nuts, eggs, seafood, etc.
  • Kiwi, bananas, chestnuts, and mangoes
  • Latex allergy
  • Cosmetics
  • Jewelry, particularly nickel jewelry
  • Nettles, poison ivy, and poison oak
  • Certain medicines, such as antibiotics, nonsteroidal anti-inflammatory drugs (such as aspirin), and hypertension drugs (such as angiotensin-converting enzyme inhibitors)

Physical triggers

The following are the few physical factors that cause allergic bumps:

  • Exposure to sunlight
  • Extreme temperature changes
  • Scratching skin
  • The pressure of something, for example, a tight belt, etc.
  • Increased body temperature due to sweating, anxiety, and exercise
  • Any stressful conditions
  • Ultraviolet light
  • In very rare cases, skin moisture and vibrations may trigger an allergic reaction

Underlying health conditions

Some health conditions that cause allergic bumps are:


Allergies can best be described as: See Answer

What are the symptoms of hives?

Symptoms of hives include:

  • They appear as raised bumps in any area of the body
  • Appears in batches
  • Mostly, they are pink, reddish, or skin-colored bumps
  • They tend to be itchy
  • If the person presses gently on the lesion, the color may go away and turn into pale color
  • Bumps usually last not more than 24 hours; a batch disappears and other bumps start or appear in another area
  • The size of the bumps could be quite tiny or large

The time taken for the lesions to appear depends on the cause of the reaction, but may include:

  • In cases of contact urticaria, the reaction typically occurs within 10 to 60 minutes of exposure and lasts for about 24 hours.
  • In cases of food allergies, the allergic bumps start appearing after an hour, and in reactions to food coloring and other additives, the allergic bumps generally appear after 12 to 24 hours.
  • For reaction to medicines, the allergic bumps appear soon after taking medicine or sometimes much later and may even persist after you stop taking the drug.

The hives may occur in any part of the body but are mostly seen on the hands, legs, and face.

How to diagnose urticaria

For treatment, hives should be diagnosed first.

  • The doctor examines the affected areas and examines them properly
  • They may ask the following questions:
    • When and where did the rash appear?
    • Were you exposured to allergens, such as insect bites, chemicals, latex, or any foods?
    • Are you taking any medications or herbal supplements?
    • What is your personal medical and family history?
  • They may order blood tests to diagnose any underlying condition that could be causing the symptoms

What are the possible treatment options for urticaria?

The following are possible ways to prevent and treat urticaria:

  • Do not scratch or rub at the area of the lesions
  • Wear loose and comfortable clothes
  • Wash your hands after touching pets
  • Wear proper warm clothes in cold weather
  • Avoid using harsh chemicals or fragrances on the skin
  • Remove any jewelry that may cause allergy (particularly nickel jewelry)
  • Wear sunscreen and protective clothing while stepping into the sun
  • Over-the-counter or prescription antihistamines
  • Corticosteroids, oral, or topical could be prescribed
Medically Reviewed on 10/27/2022
Image Source: iStock image

Hives (Urticaria). https://www.webmd.com/skin-problems-and-treatments/picture-of-hives-urticaria

Hives. https://my.clevelandclinic.org/health/diseases/8630-urticaria-hives-and-angioedema

Hives. https://www.nationwidechildrens.org/conditions/hives