Common. No decongestant is really going to help for a cold. Colds tend to last up to 2 weeks. Saline nasal washes work well to get the mucus out, regardless of cause. Rinses can also flush out pollen if allergies are contributing to the problem. Antihistamines otc can help if allergies are an issue. If problems persist over 2 weeks or difficulty breathing develops, see your doctor.
Congestion x 1 week+. Nasal congestion for a week is most likely the result of an upper respiratory tract infection or cold. This is typically viral in origin and most effectively managed by staying hydrated and otc medicine that contains a decongestant if needed. Ultimately time is the best medicine. If your are very uncomfortable and having a hard time breathing, visit your doctor.