Final answer:
A night cough may indicate an adverse reaction in a client taking propranolol, as the medication can exacerbate or cause respiratory symptoms.
Step-by-step explanation:
A client taking propranolol, which is a beta-blocker medication, may experience a variety of adverse effects. Among the options provided, a night cough could potentially indicate an adverse reaction. Propranolol can sometimes exacerbate or cause respiratory symptoms such as wheezing or cough due to its effect on the lungs' beta receptors. Although less common than other side effects, respiratory issues warrant attention and should be reported to a healthcare provider as they could signify an adverse effect, especially in clients with pre-existing respiratory conditions. The other symptoms listed (tinnitus, excessive tearing, and increased salivation) are not typically associated with the adverse effects of propranolol.