the success rate of overdosing on random OTC drugs, and even on the vast majority of prescription drugs, is comparable to that of cutting impulsively, and dying from cutting is extremely unlikely. only medical professionals and people with vast medical knowledge die from these two methods reliably, there is still a chance if you know what you are doing or are extremely lucky.
unless you have a specific allergy or a bad reaction to one of the drugs that you are taking, you are most likely going to suffer a lot and wake up on the emergency room with tubes coming in and out of every single hole in your body.