People can mistake allergy symptoms for colds, stomach bugs, and common rashes.
While common allergies are often mild, some can be serious.
If you think you have an allergy, you should see a doctor. They can test you to find out what's causing your allergic reaction and suggest a treatment.
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Allergies are an immune system reaction to a substance in the environment.
In an allergy, the immune system mistakes a chemical in food, the air, or an insect, as if it's harmful. Allergy symptoms like sneezing, swelling, and vomiting are the body's attempts to flush out the allergen.
Around a third of people in the U.S. have allergies each year. Pollen allergies are the most common.
There are many types of allergies.
They include:
An allergic reaction happens when the immune system makes antibodies to target a foreign substance.
It's not clear why the immune system overreacts.
With food allergies, research shows that a lack of exposure early in life can lead to an allergy later. For instance, parents can introduce peanuts at around 6 months of age.
Sometimes, allergens can cause anaphylaxis — a life-threatening allergic reaction that leads to very low blood pressure and trouble breathing.
Symptoms often occur throughout the body and come on within minutes to an hour of exposure.
In rare cases, anaphylaxis can lead to organ damage and even death.
People with an anaphylactic reaction need treatment right away.
Back to topAllergy symptoms can include one or more of the following:
The symptoms depend on how severe your allergy is and how you came into contact with the allergen.
For instance, if you breathe in the allergen, you may have symptoms in your nose, eyes, and mouth. If you eat the allergen, you may vomit or have diarrhea.
If someone shows signs of anaphylaxis, they need to see a doctor right away.
Signs of anaphylaxis include:
Your doctor will first ask about your symptoms, including what happened and how long the symptoms lasted.
They will also ask questions to figure out what the allergen was, such as:
Your doctor will also ask about how you treated your symptoms. If an over-the-counter anti-allergy treatment helped, an allergy is likely.
There are tests for allergies, but these tests aren't always 100% certain.
Your doctor may need to try more than one test. They may combine tests with your symptom history to make a diagnosis.
The nurse or doctor will:
Skin tests can diagnose common allergies, including to certain types of pollen, dust mites, and foods.
But skin tests aren't always accurate, especially when it comes to food. The skin may react even though the allergen wouldn't cause a problem if eaten.
Blood tests may be better than skin tests for people who:
In a blood test, the doctor takes a small amount of blood and sends it to the lab. There, a lab tech adds the suspected allergen to the blood.
If your blood cells produce a high level of antibodies in response, you likely have an allergy.
This test checks for allergic reactions that happen from contact with the skin (unlike allergens you breathe in or ingest).
The doctor will place a bandage-like patch on the skin with a small amount of the allergen. They'll check under the patch after 2 or more days for allergy symptoms.
Your doctor may suggest an oral challenge test for a food or drug allergy. They won't choose this test if a serious reaction is likely.
In an oral challenge test, you consume a very small amount of the allergen in a health care clinic. The care team checks for signs of a reaction.
They can treat any serious reaction right away.
Back to topDoctors treat allergies with medicines in pill, inhaler, nasal spray, injection, or cream form.
These treatments can:
This is the most common allergy medicine, and you don't need a prescription.
Antihistamines block histamine, the chemical released in allergic reactions.
This oral or nasal spray medicine can treat mild to moderate allergy symptoms.
Many antihistamines cause you to become drowsy. If you need to stay awake to drive or work, look for a "non-drowsy" formula.
These medicines reduce the activity of the immune system.
Your doctor may suggest an oral or a cream corticosteroid based on your type of allergy.
These over-the-counter drugs reduce swelling in the nose.
They can bring short-term relief to a runny nose or watery eyes.
These medicines stop the body from releasing antihistamines. You need to take them before exposure to an allergen for them to work.
This treatment reduces or stops anaphylaxis. It relaxes muscles to stop swelling in the airways and tightens blood vessels to raise blood pressure.
Anyone at risk of anaphylaxis should carry epinephrine with them at all times.
With this treatment, people get a shot or an oral form of a tiny amount of their allergen. The amount increases slowly over time so that the immune system gets used to it and doesn't react.
This can help cure certain allergies, such as:
Researchers are seeing if this can work for certain food allergies, like peanuts.
Back to topLast reviewed by Donna Geraci, CRNP on 2024-03-28.
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