What does vomiting up a thick black substance indicate? I am in good health but had this vomiting issue last night. I am 20 yrs. Old. I am a smoker.

Possible emergency. I answer you because i think you might be in an emergency situation so you should talk to someone immediately, a physician , or seek help immediately.
I . I am not sure what caused you to vomit a black substance. Hematemesis is the medical word for vomiting blood. Blood that is vomited can look black or it may be dark brown and look like coffee grounds. In some cases bright red blood is vomited. Did you eat anything really dark? Do you drink alcohol heavily? Did you have a nose bleed prior to that? Are you sure you vomited up the substance and did not cough it up?