Your immune system fights germs and protects your body from harmful substances that come from your environment. In some cases, however, your immune system reacts to a substance that isn’t harmful. This is called an allergy.
Allergies can affect many parts of your body, including your skin, eyes, airways, or digestive system. Some allergies are mild and only cause minor issues, while others can be life-threatening and require emergency medical care.
You may have different symptoms depending on which types of allergies you experience:
Anaphylaxis can lead to breathing difficulties, a hoarse voice, nausea or vomiting, a fast heartbeat, light-headedness, or a rash. In some cases, you may faint or go into shock. Anaphylaxis needs to be treated immediately.
The most common food allergies are to milk or dairy products, eggs, soy, wheat, fish, shellfish, sesame, peanuts, and other types of nuts such as walnuts, pecans, or almonds (tree nuts).
Other common allergy triggers include:
Children are more likely to have allergies. Sometimes — but not always — children grow out of allergies as they get older. Having a family history of allergies also increases your risk.
Allergy triggers aren’t always obvious. To narrow down the possibilities, track your diet and activities and make a note of when symptoms get better or worse.
To more precisely determine what your allergies may be, try allergy testing. This may require a skin test, in which tiny amounts of allergens are injected under your skin, or a blood test, in which a blood sample is drawn and tested in a laboratory.
Allergies often occur alongside asthma, a condition that leads to wheezing, breathing trouble, and coughing. Asthma is caused by an abnormal immune system reaction in your lungs and airways.
If you have allergies, you may also be more likely to get frequent sinus infections. These conditions occur when the spaces inside your skull (sinuses) become infected or swollen.
Mild allergic reactions can be treated with over-the-counter tablets, liquids, eye drops, and nasal sprays. Your doctor may be able to prescribe you stronger medication if allergies are frequently a problem or if non-prescription drugs don’t help relieve symptoms.
If you have had a severe allergic reaction in the past, your doctor may prescribe you an epinephrine shot. In the future, you can inject yourself with this shot if you start to have another reaction.
Allergies can be reduced with immunotherapy. This treatment involves getting regular small doses of allergens in a shot or in a tablet or liquid placed under your tongue. If your immune system is frequently exposed to allergens, it may stop reacting to them.
In many cases, you can avoid your allergy triggers. Regularly dust and vacuum your living space if you have a dust allergy. If hay fever is a problem, pay attention to the pollen levels in your area, which are usually available through local weather forecasts. Read food labels to avoid any foods you are allergic to.