Long COVID is a collection of health problems caused by COVID-19 that remain or appear following the initial infection. It is implausible that face masks cause long COVID, contrary to claims made online. Mask use can temporarily cause discomfort, but physiological effects are not biologically meaningful.
People online are touting the results of a Cochrane review to incorrectly claim that it shows masks “don’t work” against the coronavirus. But the primary conclusion of the review is that it’s uncertain from randomized controlled trials whether mask interventions in the community help slow the spread of respiratory illnesses.