The Asthma Center


Antihistamines are medications that have some similarities in structure to the histamines that cause allergic reactions. Histamines are released during allergic reactions. They cause sneezing, itching and watery mucus in the upper airway. Antihistamines work by attaching to the same receptors that histamines use to cause allergic symptoms. By occupying these sites, they effectively block histamines from causing allergic symptoms. Therefore antihistamines prevent the effects of histamine.

Antihistamines are effective if you have allergies. If you have allergic asthma, antihistamines may be effective in controlling your upper respiratory allergies and therefore help control your asthma. These medications may or may not play a role in the treatment of sinus disease. Many commonly used over the counter and prescription antihistamines are listed below. Some are antihistamines alone while others are combination products with decongestants, mucolytics, or drying agents. Astelin® is currently the only antihistamine available for nasal use.

Brand Name Antihistamine
Actifed® Cold and Allergy Tablets* (OTC) triprolidine 2.5mg
AccuHist® LA* (OTC) chlorpheniramine 8mg
Alavert™ Tablets (OTC) loratadine 10mg
Allegra® Tablets fexofenadine 30, 60, 180mg
Allegra-D® (12 Hr and 24 Hr) Extended-Release Tablets* fexofenadine 60, 180mg
AlleRx® Dose Pack PM Tab chlorpheniramine 8mg
Antivert® Tabs meclizine 12.5, 25, 50mg
Astelin® Nasal Spray azelastine 137mcg/spray
Atarax® Tablets and Syrup hydroxyzine 10, 25, 50mg
Atrohist® Pediatric Capsules chlorpheniramine 4mg
Atrohist® LA Tab chlorpheniramine 8mg
Benadryl® Allergy Chewables (OTC) diphenhydramine 12.5mg
Benadryl® Allergy Kapseal Capsules (OTC) diphenhydramine 25mg
Benadryl® Allergy Liquid Medication (OTC) diphenhydramine 12.5mg/5mL
Benadryl® Allergy Ultratab Tablets (OTC) diphenhydramine 25mg
Benadryl® Allergy/Congestion LiquidMedication* (OTC) diphenhydramine 12.5mg/5mL
Benadryl® Allergy/Congestion Tablets* (OTC) diphenhydramine 25mg
Chlor-Trimeton® Tablets (OTC) chlorpheniramine 4, 8, 12mg
Clarinex®/Clarinex-D® desloratadine 5mg
Clarinex Reditabs® desloratadine 5mg
Clarinex® Syrup desloratadine 0.5mg/mL
Claritin-D® 12Hr ER Tablets* (OTC) loratadine 5mg
Claritin-D® 24Hr ER Tablets* (OTC) loratadine 10mg
Claritin Reditabs® (OTC) loratadine 10mg
Claritin® Syrup (OTC) loratadine 1mg/mL
Claritin® Tablets (OTC) loratadine 10mg
Dallergy tab chlorpheniramine 4mg
Dallergy tab (extended-release) chlorpheniramine 12mg
Dallergy syrup chlorpheniramine 2mg
Deconamine® Caps (sustained-release) chlorpheniramine 8mg
Deconamine® Tablets chlorpheniramine 4mg
Deconamine® Syrup chlorpheniramine 2mg
Dimetapp® Cold & Allergy Chewable Tablets* (OTC) brompheniramine 1mg
Dimetapp® Elixir* (OTC) brompheniramine 2mg
Dimetapp® Tablets* (OTC) brompheniramine 4mg
Duradryl® Syrup* (OTC) chlorpheniramine 2mg
Dura-Vent/DA® Tablets* chlorpheniramine 8mg
Extendryl® Chewable Tablets* chlorpheniramine 2mg
Extendryl® Sr. T.D. Capsules* chlorpheniramine 8mg
Extendryl® Jr. Capsules* chlorpheniramine 4mg
Extendryl® Syrup* chlorpheniramine 2mg/5mL
Nolahist® Tablets* dye and alcohol free phenindamine tartrate 25mg
Periactin® Syrup cyproheptadine 2mg/5mL
Periactin® Tablets cyproheptadine 4mg
Phenergan® Suppositories promethazine 12.5, 25, 50mg
Phenergan® Syrup Fortis promethazine 25mg/5mL
Phenergan® Syrup Plain promethazine 6.25mg/5mL
Phenergan® Tablets promethazine 12.5, 25, 50mg
Phenergan® with Codeine promethazine 6.25mg/5mL
Poly-Histine® D ped caps* pyrilamine 8mg
Poly-Histine® D elixir* pyrilamine 4mg
Rondec® Oral Drops (1 - 18 months)* carbinoxamine 2mg
Rondec® DM Oral Drops (1 - 18 months)* carbinoxamine 2mg
Rondec® Syrup* brompheniramine 4mg/5mL
Rynatan® Tablets* chlorpheniramine 8mg
Rynatan® Suspension* chlorpheniramine 2mg/5mL
Rynatuss® Tablets* chlorpheniramine 5mg
Rynatuss® Pediatric Suspension chlorpheniramine 4mg/5mL
RYNA®-12 pyrilamine 30mg
Semprex-D® Capsules* acrivastine 8mg
Sinequan® (doxepin)** doxepin 10, 25, 50, 75, 100mg
caps & oral concentrate 10mg/mL
Sinutab® Sinus Allergy Tablets (OTC) chlorpheniramine 2mg
Tavist-1® 12 Hour Relief Tablets (OTC) clemastine fumarate 1.34mg
Trinalin® Repetab azatadine 1mg
Viravan-S®* pyrilamine 30mg/5mL
Viravan-T®* pyrilamine 25mg
Zyrtec® Chewable Tablets cetirizine 5, 10mg
Zyrtec® Syrup cetirizine 5mg/5mL
Zyrtec® Tablets cetirizine 10mg
Zyrtec D® Tablets* cetirizine 5mg


* Medication also includes a decongestant OTC = over the counter
**Medication also has antidepressant activity (at higher doses)

Antihistamine and Decongestant Combinations

Brand Name Ingredients
Allegra-D® Extended Release Tablets fexofenadine, 60mg
pseudoephedrine 120mg
AlleRx® Dose Pack AM Tab pseudoephedrine 120mg
methscopolamine 2.5mg
PM Tab chlorpheniramine 8mg
methscopolamine 2.5mg
Atrohist® Pediatric Capsules chlorpheniramine 4mg
pseudoephedrine 60mg
Atrohist® LA Tab chlorpheniramine 8mg
phenylephrine 20mg
hyoscyamine 0.19mg
scopolamine hydrobromide 0.01mg
Bellahist-D® LA chlorpheniramine 8mg
phenylephrine 20mg
hyoscyamine 0.19mg
scopolamine 0.01mg
Clarinex D® desloratadine 5mg
pseudoephedrine 240mg
Dallergy® Tab chlorpheniramine 4mg
phenylephrine 10mg
methscopolamine 1.25mg
Dallergy® Tab (extended-release) chlorpheniramine 12mg
phenylephrine 20mg
methscopolamine 2.5mg
Dallergy® Syrup chlorpheniramine 2mg
phenylephrine 10mg/5mL
methscopolamine 0.625mg
Deconamine® Caps (sustained-release) chlorpheniramine 8mg
pseudoephedrine 120mg
Deconamine® Tab chlorpheniramine 4mg
pseudoephedrine 60mg
Deconamine® Syrup chlorpheniramine 2mg/5mL
pseudoephedrine 30mg/5mL
Extendryl® Chewable Tablets chlorpheniramine 2mg
phenylephrine 10mg
methscopolamine 1.25mg
Extendryl® Sr. T.D. Capsules chlorpheniramine 8mg
phenylephrine 20mg
methscopolamine 2.5mg
Extendryl® Jr. Capsules chlorpheniramine 4mg
phenylephrine 10mg
methscopolamine 1.25mg
Extendryl® Syrup chlorpheniramine 2mg/5mL
phenylephrine 10mg/5mL
methscopolamine 1.25mg/5mL
Rondec® Oral Drops carbinoxamine 2mg/5mL
pseudoephedrine 25mg/5mL
Rondec® Syrup brompheniramine 4mg/5mL
pseudoephedrine 45mg/5mL
Ryna 12X® Suspension pyrilamine 30mg/5mL
phenylephrine 5mg/5mL
Rynatan® Tablets chlorpheniramine 9mg
phenylephrine 25mg
Rynatan® Suspension chlorpheniramine 4mg/5mL
phenylephrine 5mg/mL
Rynatuss® Tablets chlorpheniramine 5mg
ephedrine 10mg
phenylephrine 10mg
carbetapentane 60mg
Rynatuss® Pediatric Suspension chlorpheniramine 4mg/5mL
ephedrine 5mg/5mL
phenylephrine 5mg/5mL
carbetapentane 30mg/5mL
Semprex®-D Capsules acrivastine 8mg
pseudoephedrine 60mg
Viravan® T Chewables pyrilamine 30mg
phenylephrine 25mg
Viravan® S Suspension pyrilamine 30mg/5mL
phenylephrine 12.5mg/5mL
Zyrtec-D® Tablets cetirizine 5mg
pseudoephedrine 120mg
Antihistamine/Mast Cell Stabilizer  
Astelin® Nasal Spray azelastine 137mcg/spray

Risks and Precautions

Older antihistamines (for example, Benadryl®) have a drying effect. This drying effect can thicken secretions. This can lead to sinus problems. Second generation antihistamine products like Claritin, Allegra, Clarinex, Zyrtec and generic loratadine do not have drying effects.

Some common side effects of antihistamines include:

  • Fatigue and drowsiness (classical antihistamines)
  • Dry mouth, nausea, gastritis, stomach ache (classical antihistamines)
  • Dizziness, excitement, personality changes, irritability
  • Central nervous system depression if used with alcohol or other drugs
  • Tendency to worsen glaucoma, urinary tract obstructions (classical antihistamines)
  • Abnormalities of the blood
  • Slowed reflexes (classical antihistamines)