Why Do I Get Hives?

They show up at 4 p.m. on your forearm, a patch of raised pink welts that itch, then sting. By the time you’ve found a mirror there’s a second patch on your neck. Last night’s dinner is suspect number one. Or the new laundry soap. Or work.

What they look like

The NHS² describes raised bumps or patches in many shapes and sizes, anywhere on the body, that may itch, sting or burn and look pink or red on lighter skin tones. Cleveland Clinic³ says welts may blanch when you press them.

The AAD¹ says each individual hive usually fades within 24 hours, though new ones can appear as old ones go.

What sets them off

The AAD¹ groups the triggers into three. Allergic reactions to foods, medicines or insect bites. Infections, including colds and strep throat. And physical triggers such as pressure, sunlight or scratching. The NHS² adds cold or heat, plant or animal contact and immune system problems.

Often there’s no answer. The AAD¹ says many cases are termed spontaneous hives, with no identified cause. If a new food, medicine or product came right before, mention it to your clinician. For skin that’s reacting in other ways, see dry, itchy skin.

How long they last

The AAD¹ says most hives resolve in a few days to a few weeks. Hives that last longer than six weeks are classified as chronic.

Cleveland Clinic³ describes chronic hives as welts that appear at least twice per week, affecting up to 5% of people and more common in women ages 30 to 50. Most have no known cause, though about 20% of people with chronic hives also have an autoimmune condition such as lupus, thyroid disease or celiac disease, it says.

What helps

The NHS² says a pharmacist can recommend antihistamines, and that most hives improve within a few days with self-care. Cleveland Clinic³ suggests cool compresses and loose clothing. For chronic hives, Cleveland Clinic lists antihistamines and topical treatments first, and for severe cases a monthly injection called omalizumab or immune-suppressing medicines. The AAD¹ says hives can’t be cured, but they’re treatable, and a dermatologist can develop a plan that provides relief.

The play

Try this: a hive diary

When hives appear, write down the date, time, location on your body, how long each welt lasts, and what happened in the 24 hours before: foods, medicines, products, heat or cold, stress, illness.

Take photos. Hives move and fade, and a clinician won’t see them on the day you’re in the office.

If the diary shows no pattern after a few weeks, that’s information too.

When to get checked

Don’t wait if

1. Emergency

   Get emergency care right away if hives come with any of these:

2. Emergency

   Most hives are a few itchy days, and you can handle them with a diary and an antihistamine from your pharmacist. The swelling-and-breathing combination is the one to treat as an emergency.

The NHS² says to get an urgent GP appointment if hives don’t improve after 2 days, the rash spreads, it keeps coming back or you have a fever. The AAD¹ says to see a board-certified dermatologist if hives last more than six weeks.

Book an appointment if any of these fit:

• Hives haven’t improved after a couple of days
• They keep returning, or the rash is spreading
• They’ve lasted six weeks or longer
• You have a fever along with the rash

• Sudden swelling of the lips, mouth, tongue, throat or face. The NHS² says lips, mouth, throat or tongue suddenly becoming swollen is an emergency.
• Trouble breathing or swallowing, or breathing rapidly. The NHS² lists struggling to breathe as an emergency sign.
• Dizziness or a racing heart. The AAD¹ lists a racing heart among the reasons to go to an emergency room.