Which is a key step in safely applying a transdermal patch?

• A. Apply to moist skin
• B. Do not remove old patch
• C. Remove old patch
• D. Reuse the old patch

Answer: (C)

Removing the old patch before applying a new one is essential because it prevents leftover medication from the previous dose from combining with the new dose, which could cause an overdose or excessive drug exposure. It also ensures the skin is clean and dry so the new patch adheres properly and delivers the medication consistently. After removal, wash the area and apply the new patch to a different site if possible to reduce irritation. Reusing or leaving the old patch on risks double dosing, and applying to moist skin can impair adhesion and absorption.