Table of ContentsView AllTable of ContentsCommon UsesTypes of AntihistaminesCommon Side EffectsFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
Common Uses
Types of Antihistamines
Common Side Effects
Frequently Asked Questions
By preventing histamine from attaching to cellular receptors in the skin andmucus membranesof the eyes, nose, and respiratory tract, symptoms of allergy—such assneezing,itchy eyes,postnasal drip, and,hives—can be temporarily relieved.
Antihistamines may also be useful in treating motion sickness, nausea, sinusitis, and eczema.
This article explains the different uses of antihistamine drugs and lists some of the more common over-the-counter (OTC) and prescription formulations.
Mario Tama Collection / Getty Images
Common Uses of Antihistamines
Antihistamines are used to treat various allergic conditions and are available in oral, nasal, eyedrop, and injected formulations. Among the conditions they most commonly treat are allergic rhinitis, allergic conjunctivitis, and hives.
Allergic Rhinitis (Hay Fever)
Allergic rhinitis, also known as hay fever, is an allergic response that causes sneezing, runny nose, and itchy, watery eyes. It canoccur seasonallyor year-round, due primarily to tree or grass pollens. Oral antihistamines can generally improve hay fever symptoms within an hour or two.
Newer oral antihistamines, such as Xyzal (levocetirizine), Zyrtec (cetirizine), Allegra (fexofenadine), and Clarinex (desloratadine), are very effective for the treatment of hay fever.
Older antihistamines, like Benadryl (diphenhydramine), chlorpheniramine, and Vistaril (hydroxyzine) work well but can be sedating and cause other side effects.
There are alsonasal sprayslike Astelin (azelastine) and Patanase (olopatadine) that are used to treatallergic rhinitis(nasal allergy).
Zyrtec vs. Zyrtec-D for Allergies
Allergic Conjunctivitis
Many of the same allergens that cause hay fever can also causeallergic conjunctivitis. an allergic reaction involving the covering of the eye (known as theconjunctiva). These include airborne allergens (like pollen, dust, perfume, and pet dander) but also substances placed in or around the eye (like makeup and contact lens solution).
Oral antihistamines can help treat symptoms of eye allergies. There are also antihistamine eye drops such as Optivar (azelastine), Visine-A (pheniramine), and Alaway (ketotifen).
Urticaria (Hives)
Oral antihistamines are the main treatment for hives. Newer “non-drowsy” antihistamines, such asZyrtec or Claritin, are preferred over the older antihistamines like Benadryl or Vistaril. With that said, if the itchiness of hives is keeping you up at night talk to your provider about which treatment is best for you. Older-generation antihistamines may help you sleep more soundly.
Topical antihistamines, present in many over-the-counteranti-itch creams, should not be used with oral antihistamines. Certain ones, such as Benadryl cream, have been known to triggercontact dermatitiswhen taken with its oral version.
Other Uses
Antihistamines are used for the treatment of other allergic conditions. Some of the approved uses of antihistamines include:
OTC and Prescription Antihistamines
Not all antihistamines work equally well for all allergic conditions.
If buying an OTC antihistamine, speak with your healthcare provider or pharmacist to determine whether it is the best option for you as well as the potential risks.
OTCAlaway(ketotifen)Allegra(fexofenadine)Benadryl (diphenhydramine)Claritin (loratadine)ChlorpheniramineDimetane(brompheniramine)ClemastineVisine-A(pheniramine eyedrops)Xyzal Allergy 24HR(levocetirizine)Zyrtec (cetirizine)PrescriptionAstelin(azelastine nasal spray)Clarinex(desloratadine)Optiva(azelastine eyedrops)Palgic(carbinoxamine)Patanase(olopatadine nasal spray)Periactin(cyproheptadine)Vistaril(hydroxyzine)
OTCAlaway(ketotifen)Allegra(fexofenadine)Benadryl (diphenhydramine)Claritin (loratadine)ChlorpheniramineDimetane(brompheniramine)ClemastineVisine-A(pheniramine eyedrops)Xyzal Allergy 24HR(levocetirizine)Zyrtec (cetirizine)
Alaway(ketotifen)
Allegra(fexofenadine)
Benadryl (diphenhydramine)
Claritin (loratadine)
Chlorpheniramine
Dimetane(brompheniramine)
Clemastine
Visine-A(pheniramine eyedrops)
Xyzal Allergy 24HR(levocetirizine)
Zyrtec (cetirizine)
PrescriptionAstelin(azelastine nasal spray)Clarinex(desloratadine)Optiva(azelastine eyedrops)Palgic(carbinoxamine)Patanase(olopatadine nasal spray)Periactin(cyproheptadine)Vistaril(hydroxyzine)
Astelin(azelastine nasal spray)
Clarinex(desloratadine)
Optiva(azelastine eyedrops)
Palgic(carbinoxamine)
Patanase(olopatadine nasal spray)
Periactin(cyproheptadine)
Vistaril(hydroxyzine)
Second-generation antihistamines (like Allegra, Claritin, clemastine, Xyzal, and Zyrtec) tend to have far fewer side effects than older-generation versions. Common side effects include:
First-generation antihistamines (such as Benadryl, chlorpheniramine, and Vistaril) also have these side effects but can cause additional ones as well, including:
Because first-generation drugs are more sedating, they are generally avoided for daytime use. They can also diminish your ability to operate motor vehicles or heavy machinery.
Of the second-generation antihistamines, Allegra is the only one that is truly considered to be non-sedating.
Certain antihistaminesmay also cause weight gain. According to the American Academy of Asthma, Allergy & Immunology, both older drugs like Periactan and newer ones like Allegra and Zyrtec are linked to an increased risk ofobesity.
It is thought that the suppression of histamine, which is known to reduce appetite, can increase appetite in people on chronic antihistamine treatment.
Zyrtec (Cetirizine) vs. Benadryl (Diphenhydramine)
Summary
A Word From Verywell
As useful antihistamines are in treating allergy symptoms, they can cause problems if overused. This includes the risk of dependency if antihistamine eyedrops are overused.
If you suffer from chronic allergies and find that you need to take antihistamines every day, it may be time to ask your healthcare provider for a referral to a specialist known as anallergist.
An allergist can perform tests to see which allergens you are reacting to. They may then be able to reduce your sensitivity to these allergens with allergy shots and other forms ofallergy immunotherapy.
Do Allergy Shots Really Work?
Antihistamines can be either H1 blockers or H2 blockers, named for the histamine receptor they block. H1 blockers like Allegra (fexofenadine) and Zyrtec (cetirizine) are typically used to treat seasonal or environmental allergies. H2 blockers like Pepcid (famotidine) and Tagamet HB (cimetidine) are commonly used to reduce stomach acid.
Antihistamines generally have a low risk of abuse. However, there have been reports of people becoming dependent on older antihistamines like Benadryl (diphenhydramine) if taken at high doses for extended periods of time. Withdrawal may occur once the drug is stopped.
9 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Scadding GK.Optimal management of allergic rhinitis.Arch Dis Child. 2015;100(6):576-82. doi:10.1136/archdischild-2014-306300Church MK, Church DS.Pharmacology of antihistamines.Indian J Dermatol. 2013;58(3):219-24. doi:10.4103/0019-5154.110832Ross A, Fleming D.Hayfever–practical management issues.Br J Gen Pract. 2004;54(503):412-4. PMID: 15186559Rathi VM, Murthy SI.Allergic conjunctivitis.Community Eye Health.2017;30(99):S7–S10.Bernstein JA, Lang DM, Khan DA, et al.The diagnosis and management of acute and chronic urticaria: 2014 update.J Allergy Clin Immunol. 2014;133(5):1270-7. doi:10.1016/j.jaci.2014.02.036University of Maryland Center of Excellence in Regulatory Science and Innovation.Diphenhydramine chloride.American Academy of Asthma, Allergy & Immunology.Antihistamines and weight gain.MedlinePlus.H2 blockers.Gracious B, Abe N, Sundberg J.The importance of taking a history of over-the-counter medication use: a brief review and case illustration of “PRN” antihistamine dependence in a hospitalized adolescent.J Child Adolesc Psychopharmacol. 2010;20(6):521–4. doi:10.1089/cap.2010.0031Additional ReadingSeresirikachorn K, Khattiyawittayakun L, Chitsuthipakorn W, Snidvongs K.Antihistamines for treating rhinosinusitis: systematic review and meta-analysis of randomised controlled studies.J Laryngol Otol. 2018;132(2):105-10. doi:10.1017/S002221511700192X.
9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Scadding GK.Optimal management of allergic rhinitis.Arch Dis Child. 2015;100(6):576-82. doi:10.1136/archdischild-2014-306300Church MK, Church DS.Pharmacology of antihistamines.Indian J Dermatol. 2013;58(3):219-24. doi:10.4103/0019-5154.110832Ross A, Fleming D.Hayfever–practical management issues.Br J Gen Pract. 2004;54(503):412-4. PMID: 15186559Rathi VM, Murthy SI.Allergic conjunctivitis.Community Eye Health.2017;30(99):S7–S10.Bernstein JA, Lang DM, Khan DA, et al.The diagnosis and management of acute and chronic urticaria: 2014 update.J Allergy Clin Immunol. 2014;133(5):1270-7. doi:10.1016/j.jaci.2014.02.036University of Maryland Center of Excellence in Regulatory Science and Innovation.Diphenhydramine chloride.American Academy of Asthma, Allergy & Immunology.Antihistamines and weight gain.MedlinePlus.H2 blockers.Gracious B, Abe N, Sundberg J.The importance of taking a history of over-the-counter medication use: a brief review and case illustration of “PRN” antihistamine dependence in a hospitalized adolescent.J Child Adolesc Psychopharmacol. 2010;20(6):521–4. doi:10.1089/cap.2010.0031Additional ReadingSeresirikachorn K, Khattiyawittayakun L, Chitsuthipakorn W, Snidvongs K.Antihistamines for treating rhinosinusitis: systematic review and meta-analysis of randomised controlled studies.J Laryngol Otol. 2018;132(2):105-10. doi:10.1017/S002221511700192X.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Scadding GK.Optimal management of allergic rhinitis.Arch Dis Child. 2015;100(6):576-82. doi:10.1136/archdischild-2014-306300Church MK, Church DS.Pharmacology of antihistamines.Indian J Dermatol. 2013;58(3):219-24. doi:10.4103/0019-5154.110832Ross A, Fleming D.Hayfever–practical management issues.Br J Gen Pract. 2004;54(503):412-4. PMID: 15186559Rathi VM, Murthy SI.Allergic conjunctivitis.Community Eye Health.2017;30(99):S7–S10.Bernstein JA, Lang DM, Khan DA, et al.The diagnosis and management of acute and chronic urticaria: 2014 update.J Allergy Clin Immunol. 2014;133(5):1270-7. doi:10.1016/j.jaci.2014.02.036University of Maryland Center of Excellence in Regulatory Science and Innovation.Diphenhydramine chloride.American Academy of Asthma, Allergy & Immunology.Antihistamines and weight gain.MedlinePlus.H2 blockers.Gracious B, Abe N, Sundberg J.The importance of taking a history of over-the-counter medication use: a brief review and case illustration of “PRN” antihistamine dependence in a hospitalized adolescent.J Child Adolesc Psychopharmacol. 2010;20(6):521–4. doi:10.1089/cap.2010.0031
Scadding GK.Optimal management of allergic rhinitis.Arch Dis Child. 2015;100(6):576-82. doi:10.1136/archdischild-2014-306300
Church MK, Church DS.Pharmacology of antihistamines.Indian J Dermatol. 2013;58(3):219-24. doi:10.4103/0019-5154.110832
Ross A, Fleming D.Hayfever–practical management issues.Br J Gen Pract. 2004;54(503):412-4. PMID: 15186559
Rathi VM, Murthy SI.Allergic conjunctivitis.Community Eye Health.2017;30(99):S7–S10.
Bernstein JA, Lang DM, Khan DA, et al.The diagnosis and management of acute and chronic urticaria: 2014 update.J Allergy Clin Immunol. 2014;133(5):1270-7. doi:10.1016/j.jaci.2014.02.036
University of Maryland Center of Excellence in Regulatory Science and Innovation.Diphenhydramine chloride.
American Academy of Asthma, Allergy & Immunology.Antihistamines and weight gain.
MedlinePlus.H2 blockers.
Gracious B, Abe N, Sundberg J.The importance of taking a history of over-the-counter medication use: a brief review and case illustration of “PRN” antihistamine dependence in a hospitalized adolescent.J Child Adolesc Psychopharmacol. 2010;20(6):521–4. doi:10.1089/cap.2010.0031
Seresirikachorn K, Khattiyawittayakun L, Chitsuthipakorn W, Snidvongs K.Antihistamines for treating rhinosinusitis: systematic review and meta-analysis of randomised controlled studies.J Laryngol Otol. 2018;132(2):105-10. doi:10.1017/S002221511700192X.
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