Assuming you have no allergies, helixa syrup (natural product) may be an over-the-counter choice. What limits your choices is firstly products containing decongestants as they may increase blood pressure and/or increase your heart rate. Secondly, venlafaxine may also interact with the usual cough medicine DM. For this reason, and given our inability to switch, Helixa is an interesting choice. There are also codeine syrups sold behind the counter, however, you must opt for a formulation without decongestants. Moreover, these syrups make you sleepy and can limit your activities. I also remind you that coughs can be treated with lozenges, sinus rinses, cups of honey, moistening the room or sleeping on several pillows. I hope to have answered your question. Have a nice day