Lungs and airways

Shown to protect against the drop in lung function after exercise, with about 18 percentage points less fall in FEV1 than placebo after a single dose.

Compared with placebo [2][1]

Shown to improve lung function slightly and daily breathlessness in stable COPD compared with placebo, and people preferred it to placebo about 9 times as often.

Compared with placebo [3]

Shown to cut hospital admission when beta-agonists were nebulized continuously rather than in separate doses in the emergency department, most in people with severe airway obstruction.

Compared with intermittent nebulized beta-agonist [5]

Shown to about double quit rates against placebo with nortriptyline in a Cochrane review of six trials.

Compared with placebo [14]; bupropion [14]

Shown to reduce sore throat at day 3 against placebo, with fewer than 6 treated for one extra person without it, though 82% on placebo were symptom-free by one week.

Compared with placebo or no treatment [3]

Shown to cut COPD flare-ups with long-term macrolides such as azithromycin, from 61% to 47% of people, 8 treated for one fewer, with hearing loss reported on azithromycin.

Compared with placebo [14]

Shown to raise VO2 max and aerobic endurance in healthy adults and athletes, though results varied widely across small trials.

Shown to lower the odds of colds and shorten them in healthy people taking yeast beta-glucan, across few trials with high heterogeneity.

Shown to raise quit rates against placebo, with about 1.9 times the odds, in a Cochrane review of six small trials, with frequent dry mouth and sedation.

Compared with placebo [8]

Shown to cut repeat venous clots to 1.7% against 8.8% on placebo over a year with apixaban, and to 1.2% to 1.5% against 4.4% on aspirin with rivaroxaban.

Shown to lower respiratory infections by about 19% with probiotic fermented dairy against placebo, in one meta-analysis of 22 trials across ages.

Compared with placebo [4]

Shown to cut asthma exacerbations needing oral steroids from 15% to 11% when a long-acting beta-agonist was added to an inhaled steroid in adults.

Compared with the same dose of inhaled steroid alone [4][5]

Shown to cut exacerbations needing oral steroids by about half against a reliever alone in mild asthma, and to match regular inhaled steroids with less steroid taken.

Compared with an as-needed fast-acting bronchodilator alone [6]; as-needed albuterol [7]; regular inhaled steroid with an as-needed reliever [6][7]

Shown to cut asthma exacerbations by about a third against fixed-dose combination controllers, 6.4 fewer per 100 people aged 12 and older.

Compared with the same or higher dose of inhaled steroid and long-acting beta-agonist as controller, or inhaled steroid alone [8]

Shown to reduce COPD exacerbations by about 0.2 to 0.3 a year and slow the decline in quality of life, with no effect on deaths.

Compared with placebo [9]

Shown to lower COPD exacerbations to about 0.76 a year per 1 a year on a long-acting beta-agonist alone, with no difference in deaths and more pneumonia.

Compared with the same long-acting beta-agonist alone [10]

Shown to improve lung function, daytime symptoms and night waking against placebo in mild to moderate asthma, with FEV1 up 0.22 L more than placebo in one trial.

Compared with placebo [1]

Shown to halve exacerbations needing oral steroids when added to an inhaled steroid in adults and adolescents, about 22 treated for one fewer exacerbation.

Compared with the same dose of inhaled steroid alone [3]

Shown to reduce the drop in lung function after exercise when taken 2 hours before, a 13% fall against 22% on placebo, with less protection at 24 hours.

Compared with placebo [1]

Shown to cut treatment failure in COPD flare-ups by about half, with 9 treated to prevent one, and no change in deaths.

Shown to raise the share with sore throat pain relieved at 24 hours by 12 percentage points after one low dose, mostly of dexamethasone.

Shown to lower croup symptom scores in children within 2 to 12 hours against placebo, with fewer return visits on dexamethasone than on prednisolone.

Shown to lower 28-day deaths in hospitalized COVID-19 patients, 22.9% against 25.7%, with the benefit limited to those on oxygen or a ventilator.

Shown to cut sleep apnea events by about 13 to 25 per hour more than placebo in adults with obesity, with smaller drops in those with type 2 diabetes.

Shown in a Cochrane review to improve asthma quality of life slightly at 3 months against inactive controls. Asthma symptom scores and FEV1 in liters did not clearly change.

Compared with inactive control groups [15]

Shown to slow the yearly loss of lung function to about half the rate of continued smoking, in a large trial of smokers with early airway obstruction.

Compared with people who continued to smoke [15][16]; usual care, in the randomized comparison [16]; never smokers, with current and former smokers each set against them [17]

Shown to lower death, ventilation and worsening in patients with COVID-19 when added to standard care, about 61% fewer deaths, in small trials.

Shown to help more people stop smoking than behavioral support alone or no support, in pooled trials rated low in certainty because of risk of bias.

Compared with behavioral support only or no support [1]

Shown to cut repeat venous clots by about 95% against placebo when continued after three months, in one trial of first unprovoked clots.

Shown to raise fitness modestly across systematic reviews of activity tracker trials. One crossover study found a 1.5 mL/kg/min rise in estimated fitness over 8 weeks.

Shown to shorten colds about 2.4 days when started at onset, in low-certainty evidence from children and adults.

Limited evidence: in children with nephrotic syndrome, astragalus granules were tied to fewer upper respiratory infections. A Cochrane review found no placebo-controlled trial for preventing them in children.

Limited evidence: 4 trials found better asthma control scores and lung function in people with asthma. Peak flow did not change.

Small trials found fewer cold days in air travelers, 57 against 117 on placebo. A review rated the evidence uncertain.

One trial found 24 colds on garlic against 65 on placebo over 12 weeks. Days to recovery were similar.

One trial found fewer colds and fewer cold days over 4 months on a North American ginseng extract in adults prone to colds.

One trial found a fruit and vegetable juice powder cut days with moderate or severe cold symptoms by 20% in hospital staff. No trial measuring energy was located.

One sham-controlled trial found higher VO2 max after 40 sessions in middle-aged master athletes, with 31 of 37 randomized participants analyzed.

One large trial found low-dose budesonide cut the risk of a severe asthma exacerbation by 44% over 3 years in mild persistent asthma of recent onset.

Compared with placebo [3]

Small trials found montelukast improved sleep study measures, snoring and mouth breathing in children with mild to moderate obstructive sleep apnea over short periods.

Compared with placebo [7]; nasal mometasone alone [7]

Small uncontrolled studies found snoring fell by about half or more with mouth tape or an oral patch in people with mild sleep apnea.

Compared with before taping, in the same people [1][2]

One crossover trial of 62 CPAP users who breathed through the mouth found tape added about 52 minutes of nightly CPAP use and eased daytime sleepiness and dryness.

Compared with CPAP without mouth tape for 30 days [6]

Small trials found sildenafil raised exercise capacity only at very low oxygen, about 3,900 m and above, with no change at lower altitudes.

One trial found walking distance rose about 45 to 50 m more than placebo over 12 weeks in people with pulmonary arterial hypertension.

One trial of 385 women found less breathlessness with reflexology than with lay foot manipulation or conventional care, and better physical functioning than conventional care.

Compared with lay foot manipulation [6]; conventional care [6]

One trial found estimated VO2 max rose 2.7 mL/kg/min more when a 15-minute sauna followed each exercise session for 8 weeks, in 47 sedentary adults.

Linked to fewer hospital diagnoses of pneumonia and other respiratory disease in Finnish men who used a sauna 2 or more times a week.

One trial found fewer colds over 6 months in 25 people who took regular saunas than in 25 who did not. Duration and severity did not differ.

One trial of 36 adults found 30 daily breaths against high resistance lowered systolic pressure from 135 to 126 mm Hg over 6 weeks. Sham training did not.

Compared with low-resistance sham training [11]

One trial of 183 adults found physiotherapist breathing training improved asthma quality of life and anxiety more than nurse asthma education at 6 months, not at 1 month.

Compared with nurse-delivered asthma education, to control for clinician attention [16]

One trial found cough and phlegm fell more over a year with e-cigarettes than with nicotine replacement, with no difference in wheezing or shortness of breath.

Compared with nicotine replacement therapy [4]