Final answer:
Aspirin can be used to mitigate the side effects of nicotinic acid, such as flushing and itching.
Step-by-step explanation:
The question asks which substance can be used to minimize the undesirable adverse effects of nicotinic acid. Nicotinic acid, also known as niacin, can cause various side effects such as flushing, itching, and gastrointestinal upset. To mitigate these adverse effects, aspirin can be used. Aspirin, taken about 30 minutes before niacin, works by inhibiting the production of prostaglandins which are responsible for the vasodilation that leads to flushing. It's important not to self-medicate and to consult with a healthcare provider before combining these substances.