Daughter is in pre-k, constantly coming down with a cold. will daily vitamins help her be less affected? i know washing hands, etc is very important.

See a doctor: If your kid constant get sick, you should see a doctor get a full check. Giving vitamin is not a good way to treat the problem. Vitamin does not fix all the problems.

Vitamins: Are needed only if she does not eat enough fruits and vegetables but even then it won't affect her catching the hundreds of viruses kids get in the early years of life. Children in daycare start it earlier than children who did not go to daycare.

Probably Not, Unless: If she had an explicit vitamin deficiency & the deficient vitamin level(s) were restored, possible. However, bigger issues are more likely human. Child's view key. Leaving home for pre-k & being surrounded by many children & adults she does not know, not sure she can trust, abuse by other children, etc., perceiving being rejected by mother/family, etc. Are all very threatening/challenging issues.