I am ALWAYS worried about mixing drugs together. Currently I'm taking Robitussin AC (with codeine) once a day before bed for a cough I've had for a few weeks now. This morning I woke up with an upset stomach that has continued from last night (I have IBS, irritable bowl syndrome) so I usually take Pepto bismol to calm the affects but I'm too afraid to mix the two drugs. The last time I took robitussin was last night around 9:30pm and its now 9:00am the next morning, so it hasn't quite been twelve hours yet. I'm just wondering if its okay to take Pepto bismol (the liquid cherry flavour or chewables tablets) since so much time has passed? I looked up the drug interactions checker between the two and its a moderate level interaction, but I'm not quite understanding the explaination. Any information or explanations would help. Thanks much!