Transdermal patches are adhesive patches that deliver medication through the skin into the bloodstream. They are designed to provide a controlled release of drugs over a specific period, making them a convenient option for patients who may have difficulty taking oral medications. Common uses include pain relief, hormone replacement, and smoking cessation. These patches are typically made of a backing layer, a drug reservoir, and an adhesive layer. When applied to the skin, the medication penetrates the skin barrier and enters the bloodstream, allowing for consistent therapeutic effects. Examples of medications delivered via transdermal patches include nicotine and fentanyl.