A client experiences an unexpected response to a drug given at a therapeutic dose. What type of reaction is this?

An unexpected response to a drug given at a therapeutic dose is classified as an adverse drug reaction. This type of reaction occurs when the drug causes unintended and harmful effects, even when administered at the correct dosage. Adverse drug reactions can range from mild side effects to more severe complications and can occur due to individual patient factors such as genetics, allergies, or interactions with other medications.

In this context, a therapeutic effect refers to the desired and beneficial outcome that a medication is supposed to achieve, so it does not apply when the response is unexpected and adverse. A medication error would involve mistakes in prescribing, dispensing, or administering the medication, which is not the case if the drug was given appropriately. Drug interactions occur when one medication affects the efficacy or side effects of another, which is also not relevant to a single unexpected response at a therapeutic dose.