I have been coughing clear mucus for about a month. no other symptoms. i did have a really bad cold for a couple weeks but this is lingering. allergy?

Post-viral cough?: Many people have a lingering cough for many weeks after a viral infection. At times a short-course of inhaled steroid/bronchodilator may be helpful for some. About 10% of the people end up with a sinus infection after a cold and this may require antibiotic treatment. Check with your doctor.

Maybe: Since the mucous is clear, infection is unlikely. If you have a history of allergies, then the cough could be allergy-related. Also, it's not uncommon for irritation of the upper respiratory system to persist after the cold has resolved.. Finally, coughing causes irritation & irritation causes more coughing. Humidifying your air and using an OTC cough prep regularly for a few days may help you.