For how we live.
Cochrane found a clinically important 15.2-point pain reduction across 249 trials. A reanalysis excluding trials with fewer than 70 participants put the effect below the threshold that counts as meaningful.
A Cochrane review of 251,891 participants found no effect on total, cancer or cardiovascular mortality, at high certainty for the first two. The finding is about check-ups, not about all screening.
Cochrane reviews covering more than 19,000 participants found no reduction in cold incidence from regular vitamin C, a possible reduction in duration from zinc, and a clear increase in adverse events.
Cochrane pooled 106 randomised trials in 13,631 people; a phenotype-led update reached 152 studies. The best evidence is feature-by-feature — brimonidine for redness, ivermectin and azelaic acid for pustules.
PMDD is the severe, mostly psychological form of premenstrual illness, affecting about 3.6% of women in one study. For it, SSRIs are the best-evidenced treatment, with side effects that are common and dose-related.
Seventy-three trials, and a familiar pattern: the benefit versus no treatment shrinks by a third when only the best-conducted studies are counted. The head-to-head comparisons rest on a few hundred people.