H1 receptor antagonists

Amitriptyline, formerly sold under the brand name Elavil among others, is a tricyclic antidepressant primarily used to treat major depressive disorder, and a variety of pain syndromes such as neuropathic pain, fibromyalgia, migraine and tension headaches. Due to the frequency and prominence of side effects, amitriptyline is generally considered a second-line therapy for these indications.

Cetirizine is a second-generation peripherally selective antihistamine used to treat allergic rhinitis (hay fever), dermatitis, urticaria (hives), and runny nose. It is taken by mouth. Effects generally begin within thirty minutes and last for about a day. The degree of benefit is similar to other antihistamines such as diphenhydramine, which is a first-generation antihistamine.

Loratadine, sold under the brand name Claritin among others, is a medication used to treat allergies. This includes allergic rhinitis (hay fever) and hives. It is also available in drug combinations such as loratadine/pseudoephedrine, in which it is combined with pseudoephedrine, a nasal decongestant. It is taken orally.

thumb|A box of Rispolept (Risperidone) tablets Risperidone, sold under the brand name Risperdal among others, is an atypical antipsychotic used to treat schizophrenia and bipolar disorder, as well as aggressive and self-injurious behaviors associated with autism spectrum disorder. It is taken either by mouth or by injection (i.e., subcutaneous or intramuscular). The injectable versions are long-acting and last for 2–4 weeks.

Diphenhydramine, sold under the brand name Benadryl among others, is an antihistamine and sedative. Although generally considered sedating, diphenhydramine can cause paradoxical central nervous system stimulation in some individuals, particularly at higher doses. This may manifest as agitation, anxiety, or restlessness rather than sedation. It is a first-generation H1-antihistamine and it works by blocking certain effects of histamine, which produces its antihistamine and sedative effects. Diphenhydramine is also a potent anticholinergic. It is mainly used to treat allergies, insomnia, and sym

Quetiapine ( ), sold under the brand name Seroquel among others, is an atypical antipsychotic medication used in the treatment of schizophrenia, bipolar disorder, and major depressive disorder. Despite being widely prescribed as a sleep aid due to its tranquillizing effects, the benefits of such use may not outweigh the risk of undesirable side effects. It is taken orally.

Olanzapine, sold under the brand name Zyprexa among others, is an atypical antipsychotic primarily used to treat schizophrenia and bipolar disorder. It is also sometimes used off-label in cancer patients for treatment of chemotherapy-induced nausea and vomiting and as an appetite stimulant. For schizophrenia, it can be used for both new-onset disease and long-term maintenance. It is taken by mouth or by injection into a muscle.

Mirtazapine, sold under the brand name Remeron among others, is an atypical tetracyclic antidepressant, and as such is used primarily to treat depression. Its effects may take up to four weeks but can also manifest as early as one to two weeks. It is often used in cases of depression complicated by anxiety or insomnia. The effectiveness of mirtazapine is comparable to other commonly prescribed antidepressants. It is taken by mouth.

Trazodone is an antidepressant medication used to treat major depressive disorder, anxiety disorders, and insomnia. It is a phenylpiperazine compound of the serotonin antagonist and reuptake inhibitor (SARI) class. The medication is taken orally.

Hydroxyzine, sold under the brand names Atarax and Vistaril among others, is an antihistamine medication. It is used in the treatment of itchiness, anxiety, insomnia, and nausea (including that due to motion sickness). It is used either by mouth or injection into a muscle.

alt=A box of aripiprazole 15 mg tablets.|thumb|Aripiprazole 15 mg tablets Aripiprazole, sold under the brand name Abilify, among others, is a unique atypical antipsychotic primarily used in the treatment of schizophrenia, mania in bipolar disorder, and irritability associated with autism spectrum disorder (in children and adolescents aged 6 to 17 years); other uses include as an add-on treatment for major depressive disorder, obsessive–compulsive disorder, and tic disorders. Aripiprazole is taken by mouth or via injection into a muscle.

Desloratadine, sold under the brand name Aerius among others, is a tricyclic H1 inverse agonist that is used to treat allergies. It is the major active metabolite of loratadine.

Chlorphenamine (CP, CPM), also known as chlorpheniramine, is an antihistamine used to treat the symptoms of allergic conditions such as allergic rhinitis (hay fever). It is taken orally (by mouth). The medication takes effect within two hours and lasts for about 4–6 hours. It is a first-generation antihistamine and works by blocking the histamine H1 receptor.

Dimenhydrinate, also known as diphenhydramine/8-chlorotheophylline salt and sold under the brand names Dramamine and Gravol, among others, is an over-the-counter medication used to treat motion sickness and nausea. Dimenhydrinate is a theoclate salt composed of diphenhydramine and 8-chlorotheophylline (a theophylline relative) in a 1:1 ratio.

Cyclizine, sold under a number of brand names, is a medication used to treat and prevent nausea, vomiting and dizziness due to motion sickness or vertigo. It may also be used for nausea after general anaesthesia or that which developed from opioid use. It is taken by mouth, in the rectum, or injected into a vein.

Imipramine, sold under the brand name Tofranil, among others, is a tricyclic antidepressant (TCA) mainly used in the treatment of depression. It is also effective in treating anxiety and panic disorder. Imipramine is taken by mouth.

Fexofenadine, sold under the brand name Allegra among others, is an antihistamine medication used in the treatment of allergy symptoms such as allergic rhinitis and urticaria.

Maprotiline, sold under the brand name Ludiomil among others, is a tetracyclic antidepressant (TeCA) that is used in the treatment of depression. It may alternatively be classified as a tricyclic antidepressant (TCA), specifically a secondary amine. In terms of its chemistry and pharmacology, maprotiline is closely related to such-other secondary-amine TCAs as nortriptyline and protriptyline and has similar effects to them, albeit with more distinct anxiolytic effects. Additionally, whereas protriptyline tends to be somewhat more stimulating and in any case is distinctly more-or-less non-sedat

Doxylamine is an antihistamine medication used to treat insomnia and allergies, and—in combination with pyridoxine (vitamin B6)—to treat morning sickness in pregnant women. It is available over-the-counter and is sold under such brand names as Equate or Unisom, among others; and it is used in nighttime cold medicines (e.g., NyQuil) and pain medications containing paracetamol (acetaminophen) or codeine to help with sleep. The medication is delivered chemically by the salt doxylamine succinate and is taken by mouth. Doxylamine and other first-generation antihistamines are the most widely used sl

Levocetirizine, sold under the brand name Xyzal, among others, is a second-generation antihistamine used for the treatment of allergic rhinitis (hay fever) and long-term hives of unclear cause. It is less sedating than older antihistamines. It is taken by mouth.

Ketotifen is an antihistamine medication and a mast cell stabilizer used to treat allergic conditions such as conjunctivitis (pink eye), asthma, and hives. Ketotifen is available in ophthalmic (eye drops or drug-eluting contact lenses) and oral (tablets or syrup) forms: the ophthalmic form relieves eye itchiness and irritation associated with seasonal allergies, while the oral form helps prevent systemic conditions such as asthma attacks and allergic reactions. In addition to treating allergies, ketotifen has shown efficacy in managing systemic mast cell diseases such as mastocytosis and mast

Cariprazine, sold under the brand name Vraylar among others, is an atypical antipsychotic developed by Gedeon Richter, which is used in the treatment of schizophrenia and bipolar disorder. It is also prescribed as an add-on treatment for bipolar depression and major depressive disorder. Cariprazine acts primarily as a D3 and D2 receptor partial agonist, with a preference for the D3 receptor. It is a partial agonist at the serotonin 5-HT1A receptor and acts as an antagonist at 5-HT2B and 5-HT2A receptors. It is taken by mouth. The most prevalent side effects include nausea, mild sedation, fatig

Azelastine, sold under the brand name Astelin among others, is a H1 receptor-blocking medication primarily used as a nasal spray to treat allergic rhinitis (hay fever) and as eye drops for allergic conjunctivitis. Other uses may include asthma and skin rashes for which it is taken by mouth. Onset of effects is within minutes when used in the eyes and within an hour when used in the nose. Effects last for up to 12 hours.

Ebastine is a H1 antihistamine with low potential for causing drowsiness.

Cyproheptadine, sold under the brand name Periactin among others, is a first-generation antihistamine which is used to treat allergies. In addition, it has a number of off-label uses, such as treatment of serotonin syndrome, insomnia, and use as an appetite stimulant. The drug is taken orally.

Amoxapine, sold under the brand name Asendin among others, is a tricyclic antidepressant (TCA). It is the N-demethylated metabolite of loxapine. Amoxapine first received marketing approval in the United States in 1980, approximately 10 to 20 years after most of the other TCAs were introduced in the United States.

Mianserin, sold as Tolvon and other brand names, is an atypical antidepressant used primarily for treating depression in Europe and other countries. It is a tetracyclic antidepressant (TeCA) and is closely related to mirtazapine in terms of chemical structure, actions, and effects, although mianserin has greater noradrenergic activity and less 5-HT3 receptor antagonism.

Bilastine is an antihistamine medication used to treat hives (urticaria), allergic rhinitis and itchy inflamed eyes (allergic conjunctivitis) caused by an allergy. It is a second-generation antihistamine and takes effect by selectively inhibiting the histamine H1 receptor, preventing these allergic reactions. Bilastine has an effectiveness similar to cetirizine, fexofenadine, and desloratadine.

Clemastine, also known as meclastin, is a first-generation H1 histamine antagonist (antihistamine) with anticholinergic properties (drying) and sedative side effects. Like all first-generation antihistamines, it is sedating.

Cyclobenzaprine, sold under several brand names including, historically, Flexeril, is a muscle relaxer used for muscle spasms from musculoskeletal conditions of sudden onset. It is not useful in cerebral palsy. It is taken by mouth.

Cinnarizine is an antihistamine and calcium channel blocker of the diphenylmethylpiperazine group. It is prescribed for nausea and vomiting due to motion sickness or other sources such as chemotherapy, vertigo, or Ménière's disease. Cinnarizine is one of the leading causes of drug-induced parkinsonism.

Chlorprothixene, sold under the brand name Truxal among others, is a typical antipsychotic of the thioxanthene group.

Pheniramine (trade name Avil among others) is an antihistamine with anticholinergic properties used to treat allergic conditions such as hay fever or urticaria. It has relatively strong sedative effects, and may sometimes be used off-label as an over-the-counter sleeping pill in a similar manner to other sedating antihistamines such as diphenhydramine. Pheniramine is also commonly found in eyedrops used for the treatment of allergic conjunctivitis.

Triprolidine is an over-the-counter antihistamine with anticholinergic properties. It is used to combat the symptoms associated with allergies and is sometimes combined with other cold medications designed to provide general relief for flu-like symptoms. As with many antihistamines, the most common side effect is drowsiness.

Astemizole (marketed under the brand name Hismanal, developmental code R43512) was a second-generation antihistamine drug that has a long duration of action. Astemizole was discovered by Janssen Pharmaceutica in 1977. It was withdrawn from the market globally in 1999 because of rare but potentially fatal side effects (QTc interval prolongation and related arrhythmias due to hERG channel blockade).

Tiotixene, or thiothixene, is a typical antipsychotic sold under the brand name Navane which is predominantly utilised to treat schizophrenia. Beyond its primary indication, it can exhibit a variety of effects common to neuroleptic drugs including anxiolytic, anti-depressive, and anti-aggressive properties.

Dimetindene, also sold under the brand name Fenistil, is an antihistamine/anticholinergic. It is a first generation selective H1 antagonist. Dimetindene is an atypical first generation H1 antagonist as it only minimally passes across the blood–brain barrier.

Nefazodone, sold formerly under the brand names Serzone, Dutonin, and Nefadar among others, is an atypical antidepressant medication which is used in the treatment of depression and for other uses. Nefazodone was withdrawn in most countries by 2004 (due to liver toxicity). On December 2021, it was published that despite shortage it is still available in the United States.As of February 2026 it is available in the United States in generic form. The medication is taken by mouth.

thumb|Rupafin (Rupatadine) tablets

Carbinoxamine is an antihistamine and anticholinergic agent. It is used for hay fever, vasomotor rhinitis, mild urticaria, angioedema, dermatographism and allergic conjunctivitis. Carbinoxamine is a histamine antagonist, specifically an H1-antagonist. The maleic acid salt of the levorotatory isomer is sold as the prescription drug rotoxamine.

Orphenadrine is an anticholinergic drug of the ethanolamine antihistamine class; it is closely related to diphenhydramine. It is a muscle relaxant that is used to treat muscle pain and to help with motor control in Parkinson's disease, but has largely been superseded by newer drugs. It is considered a dirty drug due to its multiple mechanisms of action in different pathways. It was discovered and developed in the 1940s.

Alimemazine (INN), also known as trimeprazine, commonly provided as a tartrate salt, is a phenothiazine derivative that is used as an antipruritic (it prevents itching from causes such as eczema or poison ivy, by acting as an antihistamine). It also acts as a sedative, hypnotic, and antiemetic for prevention of motion sickness.

Flunarizine, sold under the brand name Sibelium among others, is a drug classified as a calcium antagonist which is used for various indications. It is not available by prescription in the United States or Japan. The drug was discovered at Janssen Pharmaceutica (R14950) in 1968.

Pemirolast (INN) is a mast cell stabilizer used as an anti-allergic drug therapy. It is marketed under the tradenames Alegysal and Alamast.

Acrivastine is a medication used for the treatment of allergies and hay fever. It is a second-generation H1-receptor antagonist antihistamine (like its base molecule triprolidine) and works by blocking histamine H1 receptors.

Olopatadine, sold under the brand name Patanol among others, is an antihistamine medication used to decrease the symptoms of allergic conjunctivitis and allergic rhinitis (hay fever). It is used as eye drops or as a nasal spray. The eye drops generally result in an improvement within half an hour.

Epinastine (brand names Alesion, Elestat, Purivist, Relestat) is a second-generation antihistamine and mast cell stabilizer that is used in eye drops to treat allergic conjunctivitis. It is produced by Allergan and marketed by Inspire in the United States. It is highly selective for the H1 receptor and does not cross the blood-brain-barrier.

Mepyramine, also known as pyrilamine, is a first-generation antihistamine, targeting the H1 receptor as an inverse agonist. Mepyramine rapidly permeates the brain, often causing drowsiness.

Brompheniramine, sold under the brand name Dimetapp among others, is a first-generation antihistamine drug of the propylamine (alkylamine) class. It 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. Like the other first-generation drugs of its class, it is considered a sedating antihistamine.

Bepotastine (Talion, Bepreve) is a 2nd generation antihistamine. It was approved in Japan for use in the treatment of allergic rhinitis and urticaria/pruritus in July 2000, and January 2002, respectively. It is marketed in the United States as an eye drop under the brand name Bepreve, by ISTA Pharmaceuticals, a subsidiary of Bausch + Lomb.

Antazoline is a 1st generation antihistamine with anticholinergic properties used to relieve nasal congestion and in eye drops, usually in combination with naphazoline, to relieve the symptoms of allergic conjunctivitis. To treat allergic conjunctivitis, antazoline can be combined in a solution with tetryzoline. The drug is a Histamine H1 receptor antagonist: selectively binding to but not activating the receptor, thereby blocking the actions of endogenous histamine and subsequently leading to the temporary relief of the negative symptoms brought on by histamine.

Chlorcyclizine (Di-Paralene, Mantadil, Pruresidine, Trihistan) is a first-generation antihistamine of the diphenylmethylpiperazine group marketed in the United States and certain other countries. It is used primarily to treat allergy symptoms such as rhinitis, urticaria, and pruritus, and may also be used as an antiemetic. In addition to its antihistamine effects, chlorcyclizine has some anticholinergic, antiserotonergic, and local anesthetic properties. It has been studied as a potential treatment for various flaviviruses like hepatitis C and Zika virus.

Mizolastine (Tradename: Mizollen) is a once-daily, non-sedating antihistamine. It blocks H1 receptors and is commonly fast-acting. It does not prevent the actual release of histamine from mast cells, it only prevents histamine from binding to receptors. Side effects can include dry mouth and throat.

drugs that block the action of histamine at the H1 receptor helping to relieve allergic reactions

Azatadine (Optimine) is a first-generation antihistamine and anticholinergic drug that was synthesized in 1963 by Schering-Plough, a former American pharmaceutical company. It is a nitrogen analog of cyproheptadine.

Terfenadine is an antihistamine formerly used for the treatment of allergic conditions. It was brought to market by Hoechst Marion Roussel (now Sanofi) and was marketed under various brand names, including Seldane in the United States, Triludan in the United Kingdom, and Teldane in Australia. It was superseded by its active metabolite fexofenadine in the 1990s due to the risk of a particular type of disruption of the electrical rhythms of the heart (specifically cardiac arrhythmia caused by QT interval prolongation) and has been withdrawn from most of markets worldwide.

Opipramol, sold under the brand name Insidon among others, is an anxiolytic and tricyclic antidepressant that is used throughout Europe. Despite chemically being a tricyclic dibenzazepine (iminostilbene) derivative similar to imipramine, opipramol is not a monoamine reuptake inhibitor like most other tricyclic antidepressants, and instead acts primarily as a sigma-1 receptor agonist. It was developed by Schindler and Blattner in 1961.

Levocabastine (trade name Livostin or Livocab, depending on the region) is a selective second-generation H1 receptor antagonist which was discovered at Janssen Pharmaceutica in 1979. It is used for allergic conjunctivitis.