Also called: Hypersensitivity
Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
About Allergy
An allergy is a reaction by your immune system to something that does not bother most other people. People who have allergies often are sensitive to more than one thing. Substances that often cause reactions are:
- Pollen
- Dust mites
- Mold spores
- Pet dander
- Food
- Insect stings
- Medicines
Normally, your immune system fights germs. It is your body's defense system. In most allergic reactions, however, it is responding to a false alarm. Genes and the environment probably both play a role.
Allergies can cause a variety of symptoms such as a runny nose, sneezing, itching, rashes, swelling, or asthma. Allergies can range from minor to severe. Anaphylaxis is a severe reaction that can be life-threatening. Doctors use skin and blood tests to diagnose allergies. Treatments include medicines, allergy shots, and avoiding the substances that cause the reactions.
It sits within Ear, Nose and Throat and Immune System.
The lead U.S. institute for this subject is the National Institute of Allergy and Infectious Diseases.
When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.
Research on Allergy
13,869 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.
What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.
Research currently under way
- Trial of the Combination of Alpha-Lipoic Acid and Mirabegron in Women and in Men With ObesityNational Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- An Open-label Extension Study of XTMAB-16 in Patients With Pulmonary SarcoidosisXentria, Inc.
- Biomarkers and Respiratory Omics as New CHildren Opportunities - Study of Clinical Outcomes and Predictivity EvaluationMedical University of Warsaw
- Evaluating the Safety and Tolerability of Baricitinib in Patients With Job Syndrome With Lupus-Like Disease and/or Atopic DermatitisNational Institute of Allergy and Infectious Diseases (NIAID)
- A Long-Term Study of Navenibart in Participants With Hereditary AngioedemaAstria Therapeutics, Inc.
- The Esophageal String Test as a Diagnostic Screening Tool for Eosinophilic Esophagitis Among Africans With Dysphagia in Mali and the United StatesNational Institute of Allergy and Infectious Diseases (NIAID)
Research already completed
- The COX-2 Gene and the Immune SystemNational Institute of Environmental Health Sciences (NIEHS)
- Cause of Unexplained AnaphylaxisNational Institute of Allergy and Infectious Diseases (NIAID)
- A Community-Based Swimming and Inspiratory Muscle Training Intervention to Promote Physical Activity and Asthma Control in Children With Mild AsthmaGümüşhane Universıty
Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.
Where to read more
Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.
Start Here
- Allergic ReactionsAmerican Academy of Allergy, Asthma, and Immunology
- AllergiesMayo Foundation for Medical Education and Research
Diagnosis and Tests
- All About Allergy TestingAmerican Academy of Allergy, Asthma, and Immunology
- Allergy Blood TestNational Library of Medicine
- Allergy Skin TestNational Library of Medicine
Treatments and Therapies
- 6 Things To Know About Complementary Health Approaches for Seasonal Allergy ReliefNational Center for Complementary and Integrative Health
- Allergy Medications: Know Your OptionsMayo Foundation for Medical Education and Research
- ButterburNational Center for Complementary and Integrative Health
- Decongestants: OTC Relief for CongestionAmerican Academy of Family Physicians
- Nasal Wash TreatmentNational Jewish Health
- Suicide Warnings on MedicationsAmerican Association of Psychiatric Pharmacists
Prevention and Risk Factors
- Allergens and IrritantsNational Institute of Environmental Health Sciences
- Allergy-Proof Your HouseMayo Foundation for Medical Education and Research
Related Issues
- Allergic Bronchopulmonary Aspergillosis (ABPA)American Academy of Allergy, Asthma, and Immunology
- Allergies and Asthma: They Often Occur TogetherMayo Foundation for Medical Education and Research
- Colds, Allergies and Sinusitis - How to Tell the DifferenceAmerican Academy of Allergy, Asthma, and Immunology
- Eosinophilic Esophagitis: MedlinePlus Health TopicNational Library of Medicine
- Feel Better. Live Better. See an Allergist / ImmunologistAmerican Academy of Allergy, Asthma, and Immunology
- Is It Flu, COVID-19, Allergies, or a Cold?National Institutes of Health
- Marvels of Mucus and Phlegm: The Slime That Keeps You HealthyNational Institutes of Health
Genetics
- Allergic asthma: MedlinePlus GeneticsNational Library of Medicine
Statistics and Research
- FastStats: Allergies and Hay FeverNational Center for Health Statistics
Clinical Trials
- ClinicalTrials.gov: HypersensitivityNational Institutes of Health
- ClinicalTrials.gov: Rhinitis, Allergic, PerennialNational Institutes of Health
Medical subject headings
Clinicians and researchers index this subject under Hypersensitivity. These are the terms to use when searching medical literature.
This page is built from the MedlinePlus health topic record for Allergy, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.