Which of the following is a contraindication for loratadine?

Loratadine is an antihistamine commonly used to treat allergies, and one of its contraindications is administration to individuals under the age of one year. This is primarily due to a lack of established safety and efficacy in very young patients. For this age group, alternative treatments that are proven safe and effective are generally recommended.

While other options may indicate conditions that require caution or special consideration, they are not absolute contraindications for the use of loratadine. For instance, severe headaches or recent surgeries may warrant medical evaluation but do not directly prohibit the use of this medication. Similarly, a known allergic reaction would typically refer to a specific allergy to loratadine itself, which is an entirely different consideration. Thus, considering the specific developmental and pharmacological factors involved, individuals younger than one are advised against using loratadine.