Mental illness is not contagious. Sufferers need not wear a breathing mask, and they won’t spread their illness by sneezing on a handrail or sharing a mug.
But at the same time, depression, addiction, anxiety, and other issues do not exist in a vacuum. Those who interact regularly and intimately with the sufferer can experience an issue of their own: codependency. It’s not guaranteed – thousands of families with mentally ill members function normally – but in certain situations, codependency can be a struggle of its own.