Allergies
Allergies are immune reactions to substances that are usually harmless. Symptoms vary depending on the trigger and the part of the body affected.
About allergies
Allergies are immune reactions to substances that are usually harmless. Symptoms vary depending on the trigger and the part of the body affected.
What can cause it?
An allergy develops when the immune system reacts to a substance such as pollen, food, medicine, venom, latex, or animal dander.
The same trigger may cause mild symptoms during one exposure and a more serious reaction during another.
What a patient may notice
Symptoms vary from person to person. Possible signs may include:
- Sneezing, congestion, or itchy eyes
- Rash, hives, or swelling
- Cough, wheezing, nausea, or abdominal symptoms
How clinicians find the cause
A clinician combines the exposure history with symptom timing. Skin-prick testing, blood tests for specific antibodies, elimination plans, or supervised challenge testing may be used; unvalidated home allergy tests can be misleading.
Treatment and next steps
- 1
Treatment depends on the organ involved and the severity of the reaction.
- 2
Options include avoidance, antihistamines, nasal or skin medicines, asthma treatment, immunotherapy, and emergency epinephrine for anaphylaxis.
- 3
A personalized action plan is important for patients at risk of severe reactions.
Supporting recovery
- Keep a record of exposures, timing, symptoms, and treatments used.
- Read food and medicine labels carefully and avoid known triggers.
- Carry prescribed emergency medicine and medical identification as advised.
What to expect
Many allergies can be controlled by identifying important triggers and using an individualized treatment plan. Symptoms may be seasonal, intermittent, or long-lasting, and sensitivity can change over time. Immunotherapy can reduce symptoms for selected environmental or venom allergies, but patients at risk for a severe reaction still need an emergency plan.
Possible complications
- Anaphylaxis, a life-threatening reaction involving breathing or blood pressure
- Asthma attacks or worsening eczema, sinus, eye, or nasal symptoms
- Sleep disruption, missed activities, nutrition concerns, or medicine side effects when allergies are not well controlled
When to Contact a Medical Professional
Arrange an evaluation when symptoms are new, worsening, interfering with normal activities, or not improving as expected.
Call 911 for trouble breathing, throat or tongue swelling, fainting, or rapidly worsening symptoms.Get emergency help for severe trouble breathing, new chest pressure, fainting, seizure, sudden weakness on one side, uncontrolled bleeding, blue or gray lips, or a person who is difficult to wake.
Ways to lower risk
- Reduce exposure only to confirmed or strongly suspected triggers.
- Discuss work, school, travel, and restaurant safety plans with the care team when severe allergy risk exists.
Trusted health information
This CHS patient-education page uses original wording and links to MedlinePlus for additional information.