A nurse is caring for a client who has bipolar disorder and is taking lithium. The client reports blurred vision and ataxia. Which of the following actions should the nurse take?

A. Blurred vision and ataxia are signs of lithium toxicity. The nurse should withhold the medication and notify the healthcare provider immediately for further evaluation. B. Administering the next dose of lithium could worsen the toxicity, as these are early signs of lithium overdose. C. Propranolol is used for controlling tremors or anxiety but does not address lithium toxicity. D. Levothyroxine is used for thyroid dysfunction, which is not indicated by these symptoms.