Can you take penicillin and Tylenol together and if so what are the side effects?

Yes you can; and there shouldn't be any side effects unless you have an allergy to one or the other of the medications. Penicillin should only be taken while under a doctor's care. Tylenol should only be taken exactly according to the directions; the difference between a correct dose and a potentially serious overdose is remarkably slim with acetaminophen (paracetamol) products.