Final answer:
The priority nursing intervention for a client receiving antiemetics is to monitor their intake and output to safeguard against dehydration and to track the efficacy of the treatment.
Step-by-step explanation:
The priority nursing intervention for a client receiving antiemetic medication is to monitor intake and output. Ensuring accurate intake and output is crucial to assess the client's fluid status and to prevent dehydration, which can often occur with conditions such as vomiting for which antiemetics are prescribed. It's also important to keep the bed in a low position to prevent falls if the client becomes dizzy or lightheaded as a side effect of the medication. Providing privacy and keeping items within reach are considerations for comfort and convenience but are not the priority interventions in this case.