Hello and hope you are doing well.
Concomitant use of these three medications namely Diphenhydramine HCI 50mg and Clonazepam .5mg and Lithium Carbonate 450mg, can cause potentially excessive or prolonged CNS and respiratory depression effects. So, would caution you to not take them together.
Hope this helped and do keep us posted.
Hi Please ask a Doctor when taking Meds , be safe .