Final answer:
The recommended concentration of isopropyl alcohol for medical use on a patient's skin is typically between 60% and 70%, with 70% being preferable for its efficacy and safety.
Step-by-step explanation:
A medical assistant should use a solution of isopropyl alcohol that is typically between 60% to 70% to effectively disinfect the patient's skin. A 70% concentration of isopropyl alcohol is usually preferred for its balance in efficacy in killing microbes and safety for use on skin. This solution not only inhibits the microbial growth but also minimizes the risk of chemical irritation to the skin. Isopropyl alcohol at this concentration is a common component in hand sanitizers and is also used as a topical antiseptic. It should be applied to the affected area in a well-ventilated space due to the inhalation hazards associated with its use.