Hello and thanks for reaching out to us! I'm more than happy to answer this for you.
In your question, you don't mention exactly what product you are referring to with 'Children's Cough DM'.
However, this product name is shared between many different store-brand (i.e. generic) cough medicines, like these products available from Walgreens, CVS, and Walmart:
All of these 'Children's Cough DM' products are made and marketed to be compared to the brand name product, Children's Delsym.
All of these products contain the same active ingredient, dextromethorphan.
So, we are looking at whether or not dextromethorphan and Benadryl (which contains the active ingredient diphenhydramine) can be taken together.
Can You Use Both Together?
As mentioned in the section above, Children's Cough DM products and brand name Delsym contain the cough suppressant, dextromethorphan.
It is safe to take Benadryl (diphenhydramine), a sedating antihistamine, and dextromethorphan together. There are no know interactions between the two drugs.
In fact, it's not uncommon for some over-the-counter cough/cold products to contain both an antihistamine, like Benadryl, and dextromethorphan.
For example, Diabetic Tussin has both drugs in it.
Side Effects?
I will say that even though Benadryl and dextromethorphan can be used together (and may even be combined into a single product), both can make you a little tired.
Benadryl is well-known to cause sedation, which is why it is so commonly used as a sleep aid.
While dextromethorphan generally doesn't cause as much sedation as Benadryl, it still does cause drowsiness in some individuals. Therefore, if you combine both, just be aware you're likely to feel tired since both can have this effect.
Final Words
Thanks again for reaching out to us. Feel free to contact us with any further questions!
