Hi Ty,

If you want to informally check drug interactions, you can do so at drugs.com with their Interactions Checker.  You can also ask your pharmacist who filled the prescriptions.  It is always a good idea to fill ALL of your prescriptions at only one pharmacy so that the pharmacist can check for drug interactions.  The pharmacist has a lot of responsibility in making sure that you are kept out of danger.

Also, you should always make sure that all of your doctors know EVERY drug and supplement you are taking.  They too can/should check for possible drug interactions when prescribing new medication.  In fact, your doctor is the one to ask this type of question.

We are not medical physicians here.  But by looking at Tenuate (diethylpropion) and Cymbalta (duloxetine), there is a potential interaction between serotonin reuptake inhibitors (like Cymbalta) and stimulants or appetite suppressants (like Tenuate).  Please talk to your doctor and report any unusual or increased side-effects you notice.