Common Causes of Hives Breakouts and What to Do Right Now
Breaking out in hives can be alarming, especially when the itchy welts appear suddenly and seem to come from nowhere. The good news is that most hives are not dangerous, and many clear up on their own within hours or days. This guide covers what to do first, what might have caused it, and when to get medical help.
What to Do Right Away If You Are Breaking Out in Hives
- Check for emergency signs. Trouble breathing, throat tightness, or swelling of the tongue, lips or face means you should call 911 (see below).
- Move away from the suspected trigger. If you just ate something new, took a medication, were stung, or touched a plant or product, stop contact if you can.
- Cool your skin. Use a cool compress and take a lukewarm shower. Avoid hot water, heavy sweating and tight clothing.
- Resist scratching. It can make welts spread and irritate the skin.
- Consider an antihistamine. A non-sedating antihistamine is the usual first choice. Follow the label, and ask a doctor or pharmacist first if you are pregnant, treating a child, or taking other medicines.
- Write down what happened. Note when the hives started and what you ate, took or did beforehand.
Common Reasons for Breaking Out in Hives
- Foods: eggs, milk, nuts, fish, shellfish, wheat and soy are frequent culprits.
- Medications: antibiotics such as penicillin, aspirin and other NSAIDs, and some blood pressure and pain medicines.
- Infections: colds and other viral illnesses are among the most common triggers, particularly in children.
- Insect stings and bites, as well as contact with latex, plants or animals.
- Physical triggers: cold, heat, sweat, sunlight, pressure, exercise or scratching.
- Stress, which can bring on or worsen an outbreak.
For a fuller breakdown, read about the causes of hives and how a hives allergic reaction differs from other triggers.
Breaking Out in Hives for No Reason
It is common not to find a cause. Many people, especially those whose hives keep returning for weeks, never identify a trigger. When hives have no clear cause, doctors call them spontaneous or idiopathic. That does not mean you did something wrong, and it does not mean they cannot be treated.
Breaking Out in Hives at Night
Hives often seem to flare in the evening or overnight. Warmth from bedding, a recent hot shower, a late meal, or simply noticing the itch more when you are not busy can all play a part. Sleeping in a cool room and wearing loose cotton pajamas can help.
How Long Will the Breakout Last?
Individual welts usually fade within 24 hours, although new ones can appear. Many outbreaks last a few days, and some continue for weeks. See how long hives last for typical timelines.
When Breaking Out in Hives Is an Emergency
Treat these symptoms as an emergency and call 911 if hives appear together with shortness of breath, a hoarse voice or trouble swallowing, swelling of the face, tongue or throat, a racing heartbeat, fainting, or vomiting and severe stomach cramps soon after a food, medication or insect sting. Do not wait to see whether they pass.
Learn more about when hives are dangerous.
When to See a Doctor
Make an appointment if you keep breaking out in hives, if the outbreak lasts more than a few days, or if hives affect your sleep or daily life. Bring your notes about timing and possible triggers. Our guide to hives symptoms explains what else to watch for. The Hives Treatment Center, founded by Dr. Tiffany Young, is a San Francisco practice that evaluates and treats recurring hives in person and online.
Frequently Asked Questions
Why do I keep breaking out in hives?
Hives that return again and again may be chronic hives, which last 6 weeks or longer, or may be caused by a repeated exposure such as a food, medication or physical trigger. A doctor can help sort out which.
Can anxiety or stress make me break out in hives?
Stress does not explain every case, but it can trigger or worsen hives in some people.
Will hives leave marks?
Ordinary hives fade without scars or bruising. Welts that leave bruises or last more than a day should be checked by a doctor.
Find Lasting Relief
You do not have to keep guessing at what to do each time hives appear. Visit our hives treatment page to see the latest treatment options for your outbreak.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. If you think you are having a medical emergency, call 911.
