Which of the following is a side effect of both Benzylpenicillin and Calcium Gluconate?

Benzylpenicillin, an antibiotic, is known to potentially cause gastrointestinal side effects such as nausea, especially when administered via IV, due to its direct impact on the gastrointestinal system. Calcium gluconate, often used in cases of hypocalcemia or as an antidote, may also lead to gastrointestinal upset when given intravenously, including nausea as a side effect.

The association of nausea as a common side effect of both drugs makes it a relevant choice in this context. It's important to be aware of patient responses to medications, and recognizing nausea allows healthcare professionals to manage this side effect effectively.

Other options such as hypersensitivity reactions are more strongly associated with Benzylpenicillin, given its nature as a beta-lactam antibiotic, and while calcium gluconate can cause anaphylactic reactions, it is not a common characteristic shared with benzylpenicillin. Cardiac arrhythmias are generally not a shared side effect of these medications; however, they may occur with excessive or rapid administration of Calcium Gluconate or in specific patient populations. Headaches are less directly linked as a side effect of these agents.

Thus, nausea emerges as the most appropriate shared side effect between Benzylpenicillin and Calcium Gluconate.