Contac 12 Hour Allergy Side Effects
Generic Name: clemastine
Note: This document contains side effect information about clemastine. Some of the dosage forms listed on this page may not apply to the brand name Contac 12 Hour Allergy.
For the Consumer
Applies to clemastine: oral oral solution, oral tablets
Side effects include:
Sedation, sleepiness, dizziness, disturbed coordination, epigastric distress, thickening of bronchial secretions.
For Healthcare Professionals
Applies to clemastine: compounding powder, oral syrup, oral tablet
Nervous system side effects have included central nervous system depression which has commonly resulted in drowsiness, dizziness, and headache. Dyskinesias have rarely been reported following chronic use of antihistamines.[Ref]
Nearly all patients experience drowsiness. This drowsiness may subside in some patients with extended use. Patients should be warned against driving, as well as concomitant ingestion with alcohol and other sedative-hypnotic drugs.
Few cases of dyskinesias and tremors, often of the face, have been reported in patients whose chronic use of antihistamines extended over a period of 3 to 10 years. Some of these cases were only partially relieved by discontinuation of the drug. Haloperidol was successful in relieving symptoms.[Ref]
Ocular effects are due to the anticholinergic effects and may include blurred vision, diplopia, and dry eyes.[Ref]
A fatal case of agranulocytosis has been reported in a patient taking chlorpheniramine, pseudoephedrine, acetaminophen, dextromethorphan, phenylpropanolamine, and aspirin. Chlorpheniramine was felt to be the cause.[Ref]
Respiratory side effects have included thickening of bronchial secretions, wheezing, and tightness in the chest.[Ref]
At least one case of toxic pustuloderma has been reported during clemastine (the active ingredient contained in Contac 12 Hour Allergy) therapy.[Ref]
Dermatologic side effects have included toxic pustuloderma.[Ref]
1. Schran HF, Petryk L, Chang CT, Oconnor R, Gelbert MB "The pharmacokinetics and bioavailability of clemastine and phenylpropanolamine in single-component and combination formulations." J Clin Pharmacol 36 (1996): 911-22
2. Schuller DE, Turkewitz D "Adverse effects of antihistamines." Postgrad Med 79 (1986): 75-86
3. Thach BT, Chase TN, Bosma JF "Oral facial dyskinesia associated with prolonged use of antihistaminic decongestants." N Engl J Med 293 (1975): 486-7
4. "Product Information. Tavist (clemastine)." Sandoz Pharmaceuticals Corporation, East Hanover, NJ.
5. "Letter: Dyskinesia associated with chronic antihistamine use." N Engl J Med 294 (1976): 113
6. Turner RB, Sperber SJ, Sorrentino JV, OConnor RR, Rogers J, Batouli AR, Gwaltney JM "Effectiveness of clemastine fumarate for treatment of rhinorrhea and sneezing associated with the common cold." Clin Infect Dis 25 (1997): 824-30
7. Frolund L, Etholm B, Irander K, Johannessen TA, Odkvist L, Ohlander B, Weeke B "A multicentre study of loratadine, clemastine and placebo in patients with perennial allergic rhinitis." Allergy 45 (1990): 254-61
8. Thomas JS, Heurich AE, Ralph JW, Crane R, Shepherd DA "Double-blind, controlled study of clemastine fumarate, chlorpheniramine and placebo in patients with seasonal allergic rhinitis." Ann Allergy 38 (1977): 169-74
9. Gwaltney JM, Park J, Paul RA, Edelman DA, Oconnor RR, Turner RB "Randomized controlled trial of clemastine fumarate for treatment of experimental rhinovirus colds." Clin Infect Dis 22 (1996): 656-62
10. Kanoh T, Jingami H, Uchino H "Aplastic anaemia after prolonged treatment with chlorpheniramine ." Lancet 1 (1977): 546-7
11. Eisner EV, LaBocki NL, Pinckney L "Chlorpheniramine-dependent thrombocytopenia." JAMA 231 (1975): 735-6
12. Deringer PM, Maniatis A "Chlorpheniramine-induced bone-marrow suppression." Lancet 1 (1976): 432
13. Hardin AS "Chlorpheniramine and agranulocytosis ." Ann Intern Med 108 (1988): 770
14. Feindkoopmans A, Vandervalk PGM, Steijlen PM, Vandekerkhof PCM "Toxic pustuloderma associated with clemastine therapy." Clin Exp Dermatol 21 (1996): 293-5
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Some side effects may not be reported. You may report them to the FDA.
More about Contac 12 Hour Allergy (clemastine)
- Contac 12 Hour Allergy Side Effects
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- Drug Interactions
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- Drug class: antihistamines