Additional administration of epinephrine, often in the form of an autoinjector (Epi-pen), is required by people with such hypersensitivities.
These factors could determine which of these two drugs is better for you. However, newer antihistamines like Zyrtec and Claritin are less likely to cause this side effect. Most people experience at least 24 hours of relief after a single dose. People who take it may feel relief in as little as one hour.
Antihistamines like Zyrtec and Claritin are designed to calm the histamine reaction your body has when it’s exposed to an allergen.
Antihistamines are most commonly used to control the symptoms of allergies such as hay fever.
In these conditions they work by preventing the actions of histamine, which is a substance produced by the body as part of its natural defences.
Antihistamines are classified into two groups – the first-generation (“sedating”) and second-generation (“non-sedating”).
Sedating antihistamines cause sedation as they are highly lipid soluble and readily cross the blood brain barrier. Agents where the main therapeutic effect is mediated by negative modulation of histamine receptors are termed antihistamines; other agents may have antihistaminergic action but are not true antihistamines.In common use, the term "antihistamine" refers only to H In type I hypersensitivity allergic reactions, an allergen (a type of antigen) interacts with and cross-links surface Ig E antibodies on mast cells and basophils.H2 blockers (eg, ranitidine, famotidine) commonly are used for the treatment of heartburn and gastroesophageal reflux disease.These medications decrease gastric acid secretion in the stomach by antagonizing the effects of histamine at H2 receptors found in gastrointestinal parietal cells.Diphenhydramine (Benadryl) is the most common first-generation antihistamine found in OTC sleep aids, whether used alone or in combination with pain relievers, including acetaminophen (eg, Tylenol PM), ibuprofen (eg, Advil PM), and aspirin.