1. Overview of studies and outcomes.

Group	Study ID	Number participants	Treatment and duration	Outcome and result	Notes
1. Antitussives
Antitussives Adults	Adams	108	Moguisteine 3.5 days	Cough score (10‐point scale) MD 0.9 on day 4	NS
	Eccles	81	Codeine 4 days	16‐item cough severity score MD 1.6	NS
	Freestone	82	Codeine Single dose	5‐point symptom rating scale MD 1.0	NS
	Lee	44	Dextromethorphan Single dose	Cough severity score (3‐point scale) MD at 180 minutes 0.5	NS
	Parvez	451	Dextromethorphan Single dose	Cough recordings at 180 minutes	Significant reduction in cough counts with treatment
	Pavesi	710	Dextromethorphan Single dose	Cough recordings at 180 minutes	Significant reduction in various cough measures with treatment
Antitussives Children	Bhattacharya	120	Dextromethorphan 3 days	Composite 5‐item symptom score MD 0.4	NS
	Korppi	50	Dextromethorphan 3 days	4‐item cough symptoms score day 3 MD 0.04	NS
	Paul	100	Dextromethorphan Single dose	Composite 5‐item symptom score MD 0.79	NS
	Taylor	57	Dextromethorphan or codeine (3 arms) 3 nights	4‐item symptom score	NS
2. Expectorants
Expectorants Adults	Albrecht	378	Guaifenesin 1600 mg bd 7 days	8‐item composite symptom score, day 4 MD 2.6, P value = 0.04	NS difference at day 7, reported day 4 outcomes
	Kuhn	65	Guaifenesin 480 mg qid 30 hours	Cough recordings and patient‐rated improvement in cough frequency and severity	NS
	Robinson	239	Guaifenesin 200 mg qid 3 days	Patient rating as 'helpful' Int 75% versus Con 31%	P value < 0.01
Expectorants Children	No studies
3. Mucolytics
Mucolytics Adults	Nesswetha	99	Bromhexine 4 days	Cough frequency (cough every 2 to 4 minutes) Int 8.6% versus Con 15.2%	P value < 0.02
Mucolytics Children	Nespoli	40	Letosteine 10 days	Composite symptom score Average 2‐point difference between intervention and control favouring intervention day 4 to 10	P value < 0.01
4. Antihistamine/decongestants
Antihistamine/ decongestants Adults	Berkowitz	283	Loratadine and pseudoephedrine 5 days	3‐item cough score MD 0.2	NS
	Curley	73	Dexbrompheniramine and pseudoephedrine 7 days	4‐item cough score MD 0.6	P value < 0.05
Antihistamine/ decongestants Children	Clemens	59	Brompheniramine and phenylpropanolamine 2 days	7‐item cough scores MD 0.1	NS
	Hutton	96	Brompheniramine and phenylephrine and propanolamine 2 days	9‐item symptom score, % reported as improved Int 67% versus Con 58%	NS
5. Other combinations
Other combinations Adults	Kurth	113	Dextromethorphan plus salbutamol 3 days	% improved day 3 Int 45% versus Con 27%	P value = 0.05
	Mizoguchi	485	Combination syrup Single dose	Cough score MD 0.42, day 2	P value < 0.0001
	Thackray	70	'Vicks' 2 days, cross‐over after 24 hours	Patient preference Int 66% versus Con 27%	P value < 0.01
	Tukiainen	108	Dextromethorphan with and without salbutamol 4 days	5‐item symptom score MD 0.11	NS
Other combinations Children	Korppi	51	Dextromethorphan plus salbutamol 3 days	Cough symptoms MD 0.12, day 3	NS
	Reece	43	Combination syrups	Satisfactory antitussive response Int both 69% versus Con 57%	NS
6. Antihistamines
Antihistamines Adults	Berkowitz	91	Terfenadine 4 to 5 days	3‐item symptom score MD 0.2	NS
	Gaffey	250	Terfenadine 3.5 days	Symptom score (scores not reported)	NS
Antihistamines Children	Bhattacharya	120	Promethazine 3 days	5‐item symptom score MD 0.3	NS
	Paul	100	Diphenhydramine Single dose	5‐item symptom score MD 1.73	NS
	Sakchainanont	143	Clemastine and chlorpheniramine 3 days	4‐item symptom score, % reporting improvement Int 40% versus Con 28%	NS
7. Honey
Honey Adults	No studies
Honey Children	Avner‐Cohen	300	3 types honey (4 arms) Single dose	5‐item composite symptom score	Significant symptom reductions in all honey groups compared to controls

Con: control
 Int: intervention
 MD: mean difference
 NS: not significant
 qid: 4 times a day