If this was your prescription you would know what it is for. Since you don't know, I can only surmise that this is not your prescription. In this case you SHOULD NOT take it. Prescription drugs are no joke. Taking something not prescribed for you by your Dr can put your life in danger.
The Mylan 4250 yellow capsule pill is a Doxepin 50mgs, Sinequan. This is a drug that is used as an antidepressant. It makes you feel cool, relaxed and composed. In most cases, people use it as an antibiotic for pain. Please consult a doctor for more information.