Is it okay to take aleve 12 hours after last dosage of dayquil?

Yes, however: Yes, there are no significant interactions between Dayquil and Aleve. I do not know why you are taking these though with you taking Dayquil am guessing you have a cold/cough. Know that these medicines only treat symptoms and do not address the cause. Vitamin C, zinc and herbs like Umcka and Andrographis help fight viral infections and homeopathy can treat symptoms as well as speed recovery.