Which of the following is considered an adverse effect to penicillin that may lead to the use of ceftriaxone?

Rash is a well-known adverse effect associated with penicillin use. Various types of skin reactions can occur, ranging from mild rashes to more severe conditions, such as Stevens-Johnson syndrome, particularly in individuals with a history of allergies or other sensitivities. In pediatric patients, a rash can lead healthcare providers to reconsider the use of penicillin, especially if there's a known allergy or a previous adverse reaction.

Ceftriaxone may be chosen as an alternative antibiotic because it belongs to a different class of antibiotics (cephalosporins) and is less likely to induce similar allergic responses in patients who have experienced a rash from penicillin. This helps minimize the risk of further allergic reactions while ensuring that the patient can still receive effective antibiotic therapy.

Other adverse effects like stomach upset, anaesthesia, and fever can occur but are not primary reasons for switching from penicillin to ceftriaxone. Stomach upset may be simply a gastrointestinal side effect without implication of an allergic reaction. Anaesthesia does not correlate with the pharmacological effects or adverse reactions of penicillin. Fever may indicate an infection or a secondary reaction but does not directly necessitate the switch to ceftriaxone as an immediate response to penicillin use.