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Antihistamine

Medical Uses of Antihistamines: – Antihistamines are used to treat allergic reactions, common cold, and influenza. – They provide relief from symptoms like nasal congestion, […]

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Medical Uses of Antihistamines:
– Antihistamines are used to treat allergic reactions, common cold, and influenza.
– They provide relief from symptoms like nasal congestion, sneezing, and hives.
– Recommended for short-term treatment, especially for chronic allergies that can lead to complications like asthma and sinusitis.
– Long-term use should be supervised by a medical professional.

Types of Antihistamines:
– H1-antihistamines inhibit H1 receptors and can be sedating or non-sedating.
– H2-antihistamines target H2 receptors to treat gastrointestinal conditions.
– H3-antihistamines affect H3 receptors in the brain and have cognitive effects.
– Mast cell stabilizers prevent mast cell degranulation.

History and Society of Antihistamines:
– Antihistamines were first discovered in the 1930s, with various types developed over the years.
– Certain antihistamines have been removed from the market due to safety concerns.
– Newer antihistamines are effective in treating hives, but research on efficacy and safety remains limited.
– Research gaps exist in understanding the long-term effects and comparative efficacy of antihistamines.

Research and Potential Uses of Antihistamines:
– Limited comparative research exists on the efficacy and safety of antihistamines, mainly with short-term studies and small sample sizes.
– Some antihistamines may have potential in enhancing cancer therapy responses and inhibiting tumor growth.
– Further research is needed to explore the effectiveness of antihistamines in combating resistance to immunotherapy.

Special Populations and Related Topics:
– Antihistamines may not be suitable for certain populations like young children, pregnant individuals, or those with specific medical conditions.
– Older individuals are more prone to drowsiness from antihistamines, potentially impacting cognitive function.
– Limited understanding exists regarding the effects of antihistamines on individuals over 65 years old.
– Related topics like antileukotrienes and immunotherapy provide additional insights into the properties and effects of antihistamines.

Antihistamine (Wikipedia)

Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provides relief from nasal congestion, sneezing, or hives caused by pollen, dust mites, or animal allergy with few side effects. Antihistamines are usually for short-term treatment. Chronic allergies increase the risk of health problems which antihistamines might not treat, including asthma, sinusitis, and lower respiratory tract infection. Consultation of a medical professional is recommended for those who intend to take antihistamines for longer-term use.

Antihistamine
Drug class
Histamine structure diagram
Histamine structure
Class identifiers
Pronunciation/ˌæntiˈhɪstəmn/
ATC codeR06
Mechanism of action • Receptor antagonist
 • Inverse agonist
Biological targetHistamine receptors
 • HRH1
 • HRH2
 • HRH3
 • HRH4
External links
MeSHD006633
Legal status
In Wikidata

Although the general public typically uses the word "antihistamine" to describe drugs for treating allergies, physicians and scientists use the term to describe a class of drug that opposes the activity of histamine receptors in the body. In this sense of the word, antihistamines are subclassified according to the histamine receptor that they act upon. The two largest classes of antihistamines are H1-antihistamines and H2-antihistamines.

H1-antihistamines work by binding to histamine H1 receptors in mast cells, smooth muscle, and endothelium in the body as well as in the tuberomammillary nucleus in the brain. Antihistamines that target the histamine H1-receptor are used to treat allergic reactions in the nose (e.g., itching, runny nose, and sneezing). In addition, they may be used to treat insomnia, motion sickness, or vertigo caused by problems with the inner ear. H2-antihistamines bind to histamine H2 receptors in the upper gastrointestinal tract, primarily in the stomach. Antihistamines that target the histamine H2-receptor are used to treat gastric acid conditions (e.g., peptic ulcers and acid reflux). Other antihistamines also target H3 receptors and H4 receptors.

Histamine receptors exhibit constitutive activity, so antihistamines can function as either a neutral receptor antagonist or an inverse agonist at histamine receptors. Only a few currently marketed H1-antihistamines are known to function as inverse agonists.

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