Hives (urticaria) are red, itchy welts that can develop on any part of the skin. Hives can vary in size and may connect to form larger welts.
Acute hives are usually caused by allergies and last less than six weeks. Chronic hives are those that last more than 6 weeks.
Large welts can also occur with hives, but deeper under the skin (angioedema). Angioedema often results in eyelid, face, lip and throat swelling, and is a medical emergency.
Hives in adults and children are commonly caused by an allergic reaction. Common allergic triggers for hives include:
- Foods
- Chocolate
- Eggs
- Fruits (especially citrus fruits and fresh berries)
- Milk
- Peanuts
- Shellfish
- Soy
- Tree nuts
- Wheat
- Pollen
- Animals
- Contact with something to which you are allergic, such as latex or nickel
- Scratching the skin
- Insect bites and stings
- Parasites
- Some medications
- Allergy shots
Other common causes of hives in adults include:
- Infections, including colds and infections caused by some bacteria or fungi
- Some illnesses
- Lupus
- Thyroid disease
- Vasculitis
- Contact with chemicals
- Exercise
- Pressure on the skin, such as from sitting too long, a tight waistband, or a heavy bag carried on the shoulder
- Stress
- Exposure to sunlight (solar urticaria)
- Heat (cholinergic urticaria, also known as heat rash)
- Exposure to cold
- Water (aquagenic urticaria)
- Alcohol
- Vibration, such as clapping or mowing the lawn (vibratory urticaria)
What Are Symptoms of Hives in Adults?
Hives may occur within minutes of exposure to a trigger or they can appear as a delayed reaction after more than two hours.
Signs and symptoms of hives in adults include:
- Slightly raised, pink, or red welts (wheals)
- Can vary in size from as tiny as a pen tip to as large as a dinner plate
- Can occur alone or in a group, or connect over a larger area
- Itching (may be severe)
- Skin swelling
- Usually subsides within 24 hours in one spot but may develop in another spot
- May be accompanied by angioedema, which is swelling deeper under the skin that can cause eyelid and lip swelling
- Angioedema is a medical emergency; see a doctor if this occurs
What Is the Treatment for Hives in Adults?
Hives usually go away on their own in less than 24 hours, though new hives can develop as old ones fade, so hives can linger for several days.
For mild to moderate cases of hives, antihistamines are usually recommended to relieve itching.
Chronic hives lasting longer than six weeks are also treated with prescription antihistamines.
In addition to antihistamines, medications used to treat hives include:
- Corticosteroids (short-term use)
- Dapsone, an antibiotic that also relieves redness and swelling
- Monoclonal antibodies, for difficult-to-treat chronic hives called chronic idiopathic urticaria (CIU)
- Histamine (H-2) blockers
- Certain antidepressants in cream form can help relieve itching
- Asthma medications with antihistamines
- Immune-suppressing drugs
Severe cases of hives or angioedema may require an injection of epinephrine (EpiPen or shot of adrenaline).
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https://www.aad.org/public/diseases/a-z/hives-overview