Because the oral mucosa is highly vascularised, medi-suppliments that are absorbed through the oral mucosa directly enter the systemic circulation, bypassing the gastrointestinal tract and first pass metabolism in the liver. For some supplements and drugs, this results in rapid onset of action via a more comfortable and convenient delivery route than the intravenous route. Not all medications, however, can be administered through the oral mucosa because of the characteristics of the oral mucosa and the physicochemical properties of the supplement.
Many abusers who inject anabolic steroids use nonsterile injection techniques or share contaminated needles with other abusers. In addition, some steroid preparations are manufactured illegally under non-sterile conditions. These factors put abusers at risk for acquiring life-threatening viral infections, such as HIV and hepatitis B and C. Abusers also can develop infective endocarditis, a bacterial illness that causes a potentially fatal inflammation of the inner lining of the heart. Bacterial infections also can cause pain and abscess formation at injection sites.