Is it true that milk causes more phlegm. What foods should be avoided by people with post nasal drip, ? What food is recommended? Is chocolate bad here

Milk and phlegm. It is an old wive's tale. Someone with post nasal drip can eat whatever they like - eating certain foods won't help or hurt nasal congestion or a runny nose though warm fluids ie soup, tea etc will have a soothing effect. Chocolate isn't bad either.