Final answer:
The nurse should expect the provider to recommend that the client takes aspirin 30 minutes before niacin to reduce facial flushing, a side effect of the medication caused by prostaglandin-mediated skin reactions.
Step-by-step explanation:
When a client who has recently started taking niacin for hyperlipidemia reports experiencing facial flushing, the nurse should expect the provider to recommend taking aspirin 30 minutes before the medication. This recommendation is made because aspirin can help reduce the prostaglandin-mediated skin flushing that is a common side effect of niacin. Therefore, the correct advice would be for the client to take aspirin 30 minutes before niacin to mitigate this side effect.