In 2026, a valid medical reason for trip cancellation generally involves an unforeseen illness, injury, or medical condition that is "disabling enough" to make travel impossible or unsafe. For travel insurance to cover the claim, a licensed physician must examine the patient and formally advise against traveling before the trip is cancelled. Common examples include a sudden broken bone, a severe infection requiring hospitalization, or a new diagnosis of a serious condition like heart disease. It also extends to your traveling companions or "non-traveling family members"; if a parent at home experiences a life-threatening medical emergency, most policies consider this a covered reason. However, "pre-existing conditions" are typically excluded unless you purchased a specific waiver. Standard "mild" issues like a common cold or minor seasonal allergies are rarely accepted. The key is that the condition must be documented by a medical professional as a physical barrier to the trip's commencement, often requiring a formal letter or the completion of a medical certificate for the insurance provider to process the refund.