Allergies occur when the body’s immune system sees a substance as a harmful “invader” and overreacts to it. The substances that cause allergic reactions are called allergens, which are what trigger an immune response, also called an allergic reaction.
Allergic reactions do not cause a fever. If you have allergy symptoms and a fever, you may have another condition such as:
- Bacterial or viral infection
- Extreme sunburn
- Heat exhaustion or heat stroke
- An inflammatory condition such as rheumatoid arthritis
Some immunizations and medications may also cause a fever.
See a doctor if you have allergy symptoms along with fever.
Common allergy symptoms include:
- Itchy, watery eyes
- Itchy nose
- Runny nose
- Sneezing
- Hives
- Rash
- Swelling
- Skin redness
- Stomach cramps
- Bloating
- Vomiting
- Diarrhea
- Pain
- Tongue swelling
- Cough
- Wheezing
- Shortness of breath
- Swelling in the mouth and throat/throat closing
- Chest tightness
- Lightheadedness or fainting
- A sense of “impending doom”
- Low blood pressure (hypotension)
- Rapid and weak pulse
Some of the above symptoms may be severe and can be signs of a serious and potentially life-threatening allergic reaction (anaphylaxis). Sudden, severe, widespread reactions require emergency care.
Call 911 if you suspect someone is having a severe allergic reaction.
What Tests Can Diagnose Allergies?
Allergies are diagnosed starting with a medical history and physical exam.
Tests used to diagnose allergies may include:
- Skin prick test
- Intradermal skin test
- Blood tests (specific IgE)
- Physician-supervised challenge tests
- Patch Test
What Medications Are Used to Treat Allergies?
The first line of treatment for allergies is to avoid known allergens if possible. When this is not possible, medications used to treat allergies include:
- Nasal corticosteroids (nose sprays) for nasal allergies
- Antihistamines to help with sneezing, itching, runny nose, and hives often caused by seasonal and indoor allergies
- Mast cell stabilizers to help with itchy, watery eyes, or an itchy, runny nose
- Decongestants to reduce nasal congestion
- Corticosteroid creams or ointments to relieve itching and rash
- Oral corticosteroids to reduce swelling and stop severe allergic reactions
- Immunotherapy
- Allergy shots
- Sublingual immunotherapy (SLIT)
- Epinephrine is administered during a life-threatening anaphylaxis (severe allergic reaction)
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