Tools for Practice


#80 Antihistamines for the Common Cold: Facts on a Possible Fix?


CLINICAL QUESTION
Are antihistamines effective in treating symptoms of the common cold?


BOTTOM LINE
Antihistamines alone have little meaningful impact on the common cold. Weak evidence suggests antihistamine-combination products improve global symptoms of the cold for one in every 4 to 7 treated. “Cough and cold products should not be used in children under 6. 



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EVIDENCE
Four systematic reviews of antihistamines alone and one of antihistamine combination.  Antihistamines alone 
  • Cochrane1 review of 18 randomized controlled trials (RCTs) including 4,342 patients: Compared to placebo, antihistamines resulted in: 
    • Any improvement in severity of general symptoms at days one - two: 55.3% versus 62.3%, number needed to treat (NNT)=15 
      • But not at days >3. 
    • Inconsistent, non-clinically meaningful changes in individual symptoms on 4-5-point scales 
      • No change in nasal congestion 
      • Improved rhinorrhea on days 2 and 4 only: Best day 2, change 0.15 (95% confidence interval [CI], 0.04-0.27) 
      • Improved sneezing on days 1-4: Best day 3, change 0.31 (95% CI 0.15-0.46) 
  • Three other systematic reviews:2-4 Similar results to Cochrane review. 
Antihistamine combination 
  • Cochrane:5 Compared to placebo, 
    • Antihistamine with decongestants (12 RCTs) improved global symptoms, NNT=4 
    • Antihistamine with analgesia (3 RCTs) improved global symptoms, NNT=4-7 
    • Antihistamine with decongestant and analgesia (5 RCTs) improved global symptoms, NNT=6 
    • The included studies did not compare these combinations to products without antihistamines to assess the contribution of antihistamines on symptom improvement. 
Context:  
  • Estimated 40% of time lost from work is attributable to the common cold.6 
  • All of the studies reported are at high or unclear risk of bias.1,5 
  • Adverse events were poorly reported, but more common with antihistamines versus placebo, number needed to harm (NNH)=34.1  
    • Combination therapies may increase adverse event rates.5 
  • Benefits seen in anti-histamine combination products likely arise from the additive effects of 2-3 products with minimal individual effects.  
  • Health Canada7 recommends against using over-the-counter cold medicines in children under age 6 because 
    • Children do not benefit from antihistamines alone1 or in combinations5 
    • Antihistamines and “cough and cold preparations” are 2nd and 6th (respectively) most common substances involved in (age <5 years) pediatric deaths.8 
 updated aug 4 2016 by ricky


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Author(s):

  • Anu Joneja MD CCFP
  • G. Michael Allan MD CCFP

1. De Sutter AIM, Saraswat A, van Driel ML. Cochrane Database Syst Rev 2015;11:CD009345.

2. De Sutter AI, Lemiengre M, Campbell H, et al. Cochrane Database Syst Rev 2003; (3):CD001267.

3. D'Agostino RB Sr, Weintraub M, Russell HK, et al. Clin Pharmacol Ther 1998;64:579– 96.

4. Luks D, Anderson MR. J Gen Intern Med 1996;11:240-4.

5. De Sutter AIM, van Driel ML, Kumar AA, et al. Cochrane Database Syst Rev 2012;2:CD004976.

6. Kirkpatrick GL. Prim Care 1996;23:657-75.

7. http://healthycanadians.gc.ca/recall-alert-rappel-avis/hc-sc/2016/57622a-eng.php [Accessed 4 Aug 2016]

8. Bronstein AC, Spyker DA, Cantilena LR Jr, et al. 2010 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 28th Annual Report. Clin Toxicol (Phila). 2011 Dec;49:910-41.

Authors do not have any conflicts of interest to declare.