Purpose <p>The symptomatology associated with COVID-19 is very diverse, ranging from flu-like symptoms to those affecting olfaction, cognition or mood for long periods. The present study explored the associations between self-reported olfactory deficits and cognitive and emotional complaints in a large-scale online survey conducted among individuals who had COVID-19.</p> Methods <p>Two complementary online studies were set up, one in France and the other in Mexico, involving 3108 and 364 volunteers respectively, to investigate the link between olfactory loss in COVID-19 and self-reported cognitive and emotional changes. Cognitive and affective complaints were assessed using simple yes/no items inspired by previously published studies, but not based on standardized clinical questionnaires.</p> Results <p>A first result was that cognitive difficulties are more frequent in COVID-19 individuals with long-standing olfactory disorders than in patients who have recently developed olfactory disorders. In addition, we also showed that the prevalence of cognitive difficulties is higher in COVID-19 patients with olfactory disorders than in those without. Furthermore, cognitive difficulties in patients with long-term olfactory disorders are more strongly associated with memory difficulties than with attention difficulties. Finally, mood disorders were more frequent in COVID-19 participants with olfactory loss than in those without.</p> Conclusion <p>Taken together, these data suggest that in COVID-19, the duration of olfactory loss is a key factor, strongly associated with cognitive and affective impairment. These data should provide us with further guidance on the management of people affected, which should not simply be unimodal, targeting just one category of symptoms.</p>