A nurse is providing discharge instructions to a client who has asthma and is about to start taking theophylline (Theo-24). The nurse should tell the client that this medication might cause which of the following adverse effects?

Montelukast is a medicine used to treat and prevent asthma and allergic rhinitis. It can cause some side effects, such as stomach pain, headache, cough, or fever. However, some side effects are more serious and need to be reported to the provider.

According to the sources I found, the most serious side effect of montelukast that should be reported to the provider is depression. Depression is a mental health condition that can affect your mood, thoughts, and behavior. It can cause symptoms such as feeling sad, hopeless, or worthless; losing interest in activities you used to enjoy; having trouble sleeping or concentrating; or having thoughts of harming yourself or others.

Montelukast has been linked to neuropsychiatric events, such as agitation, aggression, sleep disturbances, suicidal thoughts and behavior (including suicide). The mechanisms underlying these events are not well understood, but they can occur at any time during treatment. Therefore, patients and caregivers should be alert for changes in behavior or new neuropsychiatric symptoms when taking montelukast. If these occur, they should discontinue montelukast and contact a healthcare provider immediately.

The other options are not listed as serious side effects of montelukast that need to be reported to the provider. Constipation, blurred vision, and palpitations are possible side effects of other medicines used to treat asthma or allergic rhinitis, such as corticosteroids, antihistamines, or beta-agonists. However, they are not specific to montelukast and may not be related to its use.

Robitussin A-C contains codeine, which is an opioid antitussive that can have sedating effects. One of the major disadvantages of using this medication is the potential for drowsiness as a side effect. This can impair the client's ability to perform tasks that require alertness and can interfere with daily activities.
The other options listed are not the major disadvantage of antitussive therapy with Robitussin A-C:
The medication is irritating to the bronchial tree: Robitussin A-C is primarily used as an antitussive (cough suppressant) rather than for its effects on the bronchial tree. While it may have some mild irritant properties due to certain ingredients, it is not considered a major disadvantage of this medication.
The client may use the medication for 14 days: The duration of use for Robitussin A-C is typically determined by the healthcare provider based on the client's condition. While prolonged use of antitussives is generally not recommended without medical supervision, the duration of use is not considered the major disadvantage of this medication.
The medication is very expensive: The cost of medication can vary, and while cost may be a consideration for some individuals, it is not considered the major disadvantage of Robitussin
A-C specifically. The major disadvantage relates more to the potential for drowsiness caused by the medication.