Some studies testing vitamin C for colds had a problem where people in the fake pill group accidentally got vitamin C too, which might have made the vitamin C look less helpful than it really is.

Taking vitamin C pills might make your cold symptoms less severe if you're a healthy person.

Taking vitamin C pills every day might make your colds less severe, according to some studies that looked at healthy people.

Taking vitamin C after you already have a cold doesn't really help you get better faster or feel less sick, according to several big studies.

Taking vitamin C pills might help a little with colds, especially for people who are under a lot of physical stress or don't get enough vitamin C from their diet.

Vitamin C helps reduce bad cold symptoms a lot (by about a quarter), but doesn't really help with mild cold symptoms. This is based on studies of over 2700 colds.