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.

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 might help people who are stressed and in cold weather get over bad colds faster, cutting the time sick by about half, but we're not totally sure because only a few studies have looked at this.

Taking vitamin C pills every day doesn't really help prevent colds for most people, according to research.