Can I take Mucinex DM with my other medications?

Hi, Janetbug!
Here are the results from the Drugs.com Interaction Checker:
https://www.drugs.com/interactions-check.php?drug_list=846-8245,758-386,276-0,2288-0,705-360,243-0,1147-0,1615-0
There is a moderate interaction between the dextromethorphan in Mucinex with your gabapentin.

"dextromethorphan gabapentin
Applies to: Mucinex DM (dextromethorphan / guaifenesin), gabapentin

Using dextromethorphan together with gabapentin may increase side effects such as dizziness, drowsiness, confusion, and difficulty concentrating. Some people, especially the elderly, may also experience impairment in thinking, judgment, and motor coordination. You should avoid or limit the use of alcohol while being treated with these medications. Also avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medications affect you. Talk to your doctor if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.
Best regards,
Wildcat