Hives vs. Anaphylaxis: When an Allergic Reaction Is Serious

Hives on their own, raised itchy welts that come and go on the skin, are uncomfortable but usually not dangerous. Anaphylaxis is a severe allergic reaction that affects more than the skin: trouble breathing, a swollen tongue or throat, vomiting, dizziness or fainting. If hives come with any of those, it's an emergency. Use an epinephrine auto-injector if you have one and call 911.

Call 911 or go to the ER if… hives or itching come with trouble breathing, wheezing, a hoarse voice, or a tight or swollen throat; your tongue or lips are swelling; you feel dizzy, faint or confused, or your heart is racing; you're vomiting or have bad stomach cramps after eating a food or being stung; or symptoms come back after you've used epinephrine. If you carry an epinephrine auto-injector, use it right away, then call 911. Don't drive yourself to urgent care for these.

What are hives?

Hives (urticaria) are raised, itchy bumps or welts that can be pink, red or skin-colored and range from the size of a pencil eraser to large patches. A key feature: individual welts usually fade within a day, while new ones pop up somewhere else. Pressing on a welt often makes the center turn pale.

Common triggers include:

• Foods such as peanuts, tree nuts, shellfish, fish, eggs, wheat and dairy
• Medicines, including some antibiotics and pain relievers
• Insect stings
• Viral infections, a very common cause in children
• Heat, cold, pressure, sweating or exercise

Often no trigger is ever found, which is frustrating but common.

What is anaphylaxis?

Anaphylaxis is an allergic reaction that involves the whole body. It usually starts within minutes to a couple of hours of contact with a trigger, most often a food, a medicine or an insect sting, and it can get worse quickly. Hives are often part of it, but not always; some people have breathing trouble or faintness with little or no rash.

The way to tell hives from anaphylaxis is to look beyond the skin. Ask:

• Breathing: any wheezing, coughing, tight chest, hoarse voice or trouble swallowing?
• Mouth and throat: swelling of the tongue, lips or throat, or a feeling that the throat is closing?
• Circulation: dizziness, weakness, fainting, pale or clammy skin, or a racing pulse?
• Stomach: vomiting, cramping or diarrhea along with the rash?

A yes to any of these after a likely trigger means treat it as anaphylaxis. Epinephrine is the first treatment, and an ER visit is still needed after using it, because symptoms can return as it wears off.

What to do for hives at home

If it's hives only, with no breathing, swelling, dizziness or stomach symptoms:

• Stop or avoid the suspected trigger, if you know it. If you think a prescription medicine is the cause, call the prescriber before stopping it.
• An over-the-counter antihistamine can ease the itch, if it's safe for you. Follow the label, and ask a pharmacist about dosing for children.
• Cool compresses, a cool shower and loose, soft clothing help. Heat and scratching tend to make hives flare.
• Keep an eye on things for the next few hours, especially after a new food, medicine or sting.

When should hives be seen at urgent care?

Come in the same day if hives are widespread or very itchy despite an antihistamine, keep coming back over several days, came on after starting a new medicine, or come with a fever or joint pain. Hives that keep returning for more than about six weeks are called chronic hives; they're worth working through with your own doctor, who may refer you to an allergist.

At a visit for rashes and hives, a clinician examines the skin, asks about what you ate, took or touched, and checks for signs of a more serious reaction. They can discuss treatment, which may include antihistamines or prescription medication. For a mild food allergy reaction, they can talk through avoiding the trigger and whether you should follow up about an epinephrine prescription or allergy testing.

For hives only, a telehealth video visit is often enough, since many rashes can be evaluated on camera or with photos. It's available daily from 8 AM to 11 PM. Telehealth is not for anything on the 911 list above.

What does it cost?

A telehealth visit is $75 self-pay. Self-pay in-clinic visits are $175 for a standard visit, $250 with one moderate service, and $330 for a procedure or two moderate services; the tier depends on the care you actually receive. If you're using insurance: we contract with all major commercial and government plans, including Colorado Medicaid and Medicare. We can't guarantee a particular commercial plan has us in network, and if you turn out to be out of network or your benefits are denied, we bill you at the self-pay rates. See our cost and insurance page for details.

Where to find us

Four clinics across metro Denver, all ages welcome, se habla español:

• Hampden (Southeast Denver): 8 AM–11 PM daily
• Littleton: 8 AM–11 PM daily
• Thornton: 8 AM–11 PM daily
• Highlands: Mon–Fri 5–11 PM, Sat–Sun 8 AM–11 PM

Walk in, or book online.