US National Library of Medicine
Medline Plus: Pseudoephedrine
Here, you can read detailed notes on pseudoephedrine, a main ingredient in many over-the-counter and prescription decongestants. This website provides responses to several questions concerning this medication including: "How should this...
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Allergy Glossary: Decongestant
This is a very brief write-up about decongestants, where you can read about how this medication can relieve congestion and how they can also cause adverse side effects.
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Medinfo: Antihistamines
A description of antihistamines which tells what they're used for, the different forms they come in, and the adverse reactions that can occur from taking them.
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American Academy of Allergy, Asthma and Immunology
This resource describes an organization that is involved in studies and treatments of allergies. Research and education are also important parts of this organization.