I took a single dose of benadryl liquid last night can i take my lorazepam today?

Yes, the remaining Benadryl left your system by about 8-12 hours after the dose.

I think that will be alright. However, why did you take the Benadryl? Do you normally take lorazepam. Please consult with your Physician who prescribes the lorazepam if you will be alright.

You can take your lorazepam today. The Benadryl is almost completely out of your system already by the next day. No concern. Good luck.