An antihistamine is a drug which serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions, through action at the histamine receptor. Only 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 H1-receptor antagonists, also known as HIncluding:

Antihistamine - Pharmacology Antihistamine - Clinical use of antihistamines
Antihistamine - Indications Antihistamine - Adverse drug reactions
Antihistamine - First-generation H1-receptor antagonists
Antihistamine - Ethylenediamines Antihistamine - Ethanolamines Antihistamine - Alkylamines Antihistamine - Piperazines Antihistamine - Tricyclics Antihistamine - Common structural features of classical antihistamine
Antihistamine - Second-generation H1-receptor antagonists
Antihistamine - Systemic Antihistamine - Topical Antihistamine - Common structural features of non-sedating antihistamines
Antihistamine - Third-generation H1-receptor antagonists
Antihistamine - Systemic
Antihistamine - Other agents
Antihistamine - Inhibitors of histamine release Antihistamine - H2-receptor antagonists Antihistamine - H3- and H4-receptor antagonists Antihistamine - Other agents with antihistaminergic activity

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Antihistamine, Antihistamine - Pharmacology, Antihistamine - Clinical use of antihistamines, Antihistamine - Indications, Antihistamine - Adverse drug reactions, Antihistamine - First-generation H1-receptor antagonists, Antihistamine - Ethylenediamines, Antihistamine - Ethanolamines, Antihistamine - Alkylamines, Antihistamine - Piperazines, Antihistamine - Tricyclics, Antihistamine - Common structural features of classical antihistamine, Antihistamine - Second-generation H1-receptor antagonists, Antihistamine - Systemic, Antihistamine - Topical, Antihistamine - Common structural features of non-sedating antihistamines, Antihistamine - Third-generation H1-receptor antagonists, Antihistamine - Systemic, Antihistamine - Other agents, Antihistamine - Inhibitors of histamine release, Antihistamine - H2-receptor antagonists, Antihistamine - H3- and H4-receptor antagonists, Antihistamine - Other agents with antihistaminergic activity

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Antihistamine - Indications. H1-antihistamines are clinically used in the treatment of histamine-mediated allergic conditions. Specifically, these indications may include: (Rossi, 2004) allergic rhinitis allergic conjunctivitis allergic dermatological conditions (contact dermatitis) urticaria angioedema pruritus (atopic dermatitis, insect bites) anaphylactic or anaphylactoid reactions - adjunct only nausea and vomiting (first-generation H1-antihistamines)

In allergic reactions an allergen (a type of antigen) interacts with and cross-links surface IgE antibodies on mast cells and basophils. Once the mast cell-antibody-antigen complex is formed, a complex series of events occurs that eventually leads to cell-degranulation and the release of histamine (and other chemical mediators) from the mast cell or basophil. Once released, histamine can react with local or widespread tissues through histamine receptors. Histamine, acting on H1-receptors, produces pruritis, vasodilatation, hypotension, flushing, headache, tachycardia, bronchoconstriction, increases vascular permeabili ...

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Antihistamine, Antihistamine - Pharmacology, Antihistamine - Clinical use of antihistamines, Antihistamine - Indications, Antihistamine - Adverse drug reactions, Antihistamine - First-generation H1-receptor antagonists, Antihistamine - Ethylenediamines, Antihistamine - Ethanolamines, Antihistamine - Alkylamines, Antihistamine - Piperazines, Antihistamine - Tricyclics, Antihistamine - Common structural features of classical antihistamine, Antihistamine - Second-generation H1-receptor antagonists, Antihistamine - Systemic, Antihistamine - Topical, Antihistamine - Common structural features of non-sedating antihistamines, Antihistamine - Third-generation H1-receptor antagonists, Antihistamine - Systemic, Antihistamine - Other agents, Antihistamine - Inhibitors of histamine release, Antihistamine - H2-receptor antagonists, Antihistamine - H3- and H4-receptor antagonists, Antihistamine - Other agents with antihistaminergic activity

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These are the oldest antihistaminergic drugs and are relatively inexpensive and widely available. They are effective in the relief of allergic symptoms, but are typically moderately to highly potent muscarinic acetylcholine receptor-antagonists (anticholinergic) agents as well. These agents also commonly have action at α-adrenergic receptors and/or 5-HT receptors. This lack of receptor-selectivity is the basis of the poor tolerability-profile of some of these agents, especially compared with the second-generation H1-antihistamines. Patient response and occurrence of a ...

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Antihistamine, Antihistamine - Pharmacology, Antihistamine - Clinical use of antihistamines, Antihistamine - Indications, Antihistamine - Adverse drug reactions, Antihistamine - First-generation H1-receptor antagonists, Antihistamine - Ethylenediamines, Antihistamine - Ethanolamines, Antihistamine - Alkylamines, Antihistamine - Piperazines, Antihistamine - Tricyclics, Antihistamine - Common structural features of classical antihistamine, Antihistamine - Second-generation H1-receptor antagonists, Antihistamine - Systemic, Antihistamine - Topical, Antihistamine - Common structural features of non-sedating antihistamines, Antihistamine - Third-generation H1-receptor antagonists, Antihistamine - Systemic, Antihistamine - Other agents, Antihistamine - Inhibitors of histamine release, Antihistamine - H2-receptor antagonists, Antihistamine - H3- and H4-receptor antagonists, Antihistamine - Other agents with antihistaminergic activity

Read more here: » Antihistamine: Encyclopedia II - Antihistamine - First-generation H₁-receptor antagonists

These are newer drugs that are much more selective for peripheral H1 receptors in preference to the central nervous system histaminergic and cholinergic receptors. This selectivity significantly reduces the occurrence of adverse drug reactions compared with first-generation agents, while still providing effective relief of allergic conditions. Antihistamine - Systemic. acrivastine astemizole cetirizine loratadine mizolastine terfenadine (withdrawn from ...

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Antihistamine, Antihistamine - Pharmacology, Antihistamine - Clinical use of antihistamines, Antihistamine - Indications, Antihistamine - Adverse drug reactions, Antihistamine - First-generation H1-receptor antagonists, Antihistamine - Ethylenediamines, Antihistamine - Ethanolamines, Antihistamine - Alkylamines, Antihistamine - Piperazines, Antihistamine - Tricyclics, Antihistamine - Common structural features of classical antihistamine, Antihistamine - Second-generation H1-receptor antagonists, Antihistamine - Systemic, Antihistamine - Topical, Antihistamine - Common structural features of non-sedating antihistamines, Antihistamine - Third-generation H1-receptor antagonists, Antihistamine - Systemic, Antihistamine - Other agents, Antihistamine - Inhibitors of histamine release, Antihistamine - H2-receptor antagonists, Antihistamine - H3- and H4-receptor antagonists, Antihistamine - Other agents with antihistaminergic activity

Read more here: » Antihistamine: Encyclopedia II - Antihistamine - Second-generation H₁-receptor antagonists

Clemastine is an over-the-counter antihistamine sold in the United States under the name Tavist. Although it is not a non-sedating antihistamine like loratadine or fexofenadine, it seems to have fewer side effects than most widely used "regular" antihistamines. Clemastine - External link. NIH Medline Plus listing on Clemastine (Acrivastine) (Astemizole) (Azelastine) (Brompheniramine) (Carbinoxamine) (Cetirizine) (Chlorphenamine) (C ...

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Clemastine - External link

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Diphenhydramine 2-(Diphenylmethoxy) -N,N-dimethylethylamine hydrochloride. Antihistaminic Motion sickness Sedative Tardive dyskinesia Other uses: Halting allergic reactions, controlling extrapyramidal side-effects induced by anticonvulsants Use in neonates and premature infants Use in nursing mothers Use as a local anesthetic Use in people with hypersensitivity to diphenhydramine hydrochloride an ...

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Chlorphenamine Chlorphenamine (INN) or chlorpheniramine (USAN, former BAN), commonly marketed as its salt chlorphenamine maleate (CPM; Chlor-Trimeton®, Piriton®), is a first-generation antihistamine used in the prevention of the symptoms of allergic conditions such as rhinitis and urticaria. Chlorphenamine has antidepressant properties, inhibiting reuptake of the neurotransmitter serotonin. Based on this knowledge, the Swedish company Astra AB was able to derive the first marketed selective serotonin ...

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These are the active enantiomer (levocetirizine, desloratadine) or metabolite (fexofenadine) derivatives of second-generation drugs intended to have increased efficacy with fewer adverse drug reactions. Indeed, fexofenadine is associated with a decreased risk of cardiac arrhythmia compared to terfenadine. However, there is little evidence for any advantage of levocetirizine or desloratadine, compared to cetirizine or loratadine respectively. Antihistamine - SystemicSee also:

Antihistamine, Antihistamine - Pharmacology, Antihistamine - Clinical use of antihistamines, Antihistamine - Indications, Antihistamine - Adverse drug reactions, Antihistamine - First-generation H1-receptor antagonists, Antihistamine - Ethylenediamines, Antihistamine - Ethanolamines, Antihistamine - Alkylamines, Antihistamine - Piperazines, Antihistamine - Tricyclics, Antihistamine - Common structural features of classical antihistamine, Antihistamine - Second-generation H1-receptor antagonists, Antihistamine - Systemic, Antihistamine - Topical, Antihistamine - Common structural features of non-sedating antihistamines, Antihistamine - Third-generation H1-receptor antagonists, Antihistamine - Systemic, Antihistamine - Other agents, Antihistamine - Inhibitors of histamine release, Antihistamine - H2-receptor antagonists, Antihistamine - H3- and H4-receptor antagonists, Antihistamine - Other agents with antihistaminergic activity

Read more here: » Antihistamine: Encyclopedia II - Antihistamine - Third-generation H₁-receptor antagonists

Hypnotic drugs are a class of drugs that induce sleep, used in the treatment of severe insomnia. These drugs include barbiturates, benzodiazepines, zolpidem, zopiclone, eszopiclone, chloral hydrate, chlormethiazole or the antihistamines doxylamine, promethazine, and diphenhydramine. Alcohol is often tried as a hypnotic drug but it is not particularly effective. Other related archivesAlcohol, Hypnosis, antihistamines, barbiturates, benzodiazepines, chloral hydrate, chlormethiazole, diph

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Antipruritic is a drug which reduces pruritis, or itching. Most anti-pruritic drugs are antihistamines or mint-like substances such as menthol or camphor. Calamine lotion is a zinc-based anti-pruritic that has been used in this capacity for hundreds of years. A commonly used herbal antipruritic is Olive Oil. Other related archivesCalamine lotion, antihistamines, camphor, itching, menthol, mint

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Chemosis is defined as the swelling of the conjunctiva. It is usually caused by allergies or viral infection. Antihistamines are used for treatment. Other related archivesAntihistamines, allergies, conjunctiva, infection, swelling, viral

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Brompheniramine Brompheniramine is an antihistaminergic medication of the propylamine class. It is commonly available over the counter and is indicated for the treatment of the symptoms of the common cold and allergic rhinitis, such as runny nose, itchy eyes, watery eyes, and sneezing. It is a first-generation antihistamine. Brompheniramine works by acting as an antagonist of the H1 histamine receptors. It also functions as a moderately effective anticholingeric agent, likely an antimuscarinic agent similar ...

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An antiemetic is a drug that is effective against vomiting and nausea. Antiemetics are typically used to treat motion sickness and the side effects of opioid analgesics and chemotherapy directed against cancer. Antiemetics include: 5-Hydroxytryptamine antagonists Dolasetron Granisetron Ondansetron Tropisetron Dopamine antagonists Domperidone Droperidol, Haloperidol, Chlorpromazine metoclopramide Antihistamines ( ...

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Entries marked with a # are naturally occurring. Deliriant - Tropanes. Atropine # Scopolamine # Hyoscyamine # 3-quinuclidinyl benzilate Deliriant - Antihistaminics. diphenhydramine (Benadryl) dimenhydrinate (Dramamine) cyclizine (Marezine or Marzine) ...

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Deliriant, Deliriant - Pharmacological classes of deliriants and their general subjective effects, Deliriant - Tropanes, Deliriant - Antihistaminics

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Histamine is released as a neurotransmitter. The cell bodies of neurons which release histamine are found in the posterior hypothalamus, in various tuberomammillary nuclei. From here, these histaminergic neurons project throughout the brain, to the cortex through the medial forebrain bundle. Histaminergic action is known to modulate sleep. Classically, antihistamines (H1 histamine receptor antagonists) produce sleep. Likewise, destruction of histamine releasing neurons, or inhibition of histamine synthesis leads to an inability to maintain vigilance. Finally, H3 receptor antagonists (which stim ...

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Histamine, Histamine - Synthesis and metabolism, Histamine - Storage and release, Histamine - Mechanism of action, Histamine - Sleep regulation, Histamine - Histamine disorder effects, Histamine - Sexual response, Histamine - Schizophrenia, Histamine - Other effects

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Promethazine (sold as Phenergan and Promethegan) is a first-generation H1 receptor antagonist (antihistamine) and anti-nausea medication available by prescription in the United States, and over-the-counter in the United Kingdom, Switzerland, Australia, South Africa, New Zealand and many other countries. Promethazine belongs to the phenothiazine class of drugs. It can be prescrib ...

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Promethazine, Promethazine - General Remarks and Pharmacology, Promethazine - Indications, Promethazine - Contraindications, Promethazine - Side Effects, Promethazine - Interactions, Promethazine - Dosage, Promethazine - Laboratory Examinations

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For symptomatic relief of carcinoid sydrome: Octreotide (somatostatin analogue- neutralizes serotonin and decreases urinary 5-HIAA) Methysergide maleate (antiserotonin agent but not used because of serious side effect of retroperitoneal fibrosis) Cyproheptadine (antihistamine) Alternative treatment for qualifying candidates: Surgical resection of tumo ...

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Carcinoid syndrome, Carcinoid syndrome - Pathophysiology, Carcinoid syndrome - Diagnosis, Carcinoid syndrome - Treatment, Carcinoid syndrome - Prognosis, Carcinoid syndrome - Synonyms

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Treatments for morning sickness typically aim to lessen the symptoms of nausea, rather than attacking the root cause(s) of the nausea. Treatments include: Avoiding an empty stomach Eating five or six small meals per day, rather than three large ones Ginger, in capsules, tea, or in ginger ale or ginger beer Pyroxidine (vitamin B6), sometimes taken in combination with the antihistamine doxylamine Accupressure applied to the P6 point on the inside of the forearm, one-sixth of the way from the wrist to the elbow Lemons, particularly smelling freshly cut ...

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Morning sickness, Morning sickness - When it occurs, Morning sickness - Causes, Morning sickness - Treatments, Morning sickness - Associations with miscarriage risk

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