If you’re thinking about the annual flu vaccine (and you should be – especially if your private health insurance or affordable health insurance plan covers it), you may already know about the usual side-effects like a sore arm or slight fever. But there are lesser-known reactions that are worth being aware of — especially given the latest updates for the 2025-2026 flu season.
Here we’ll walk through five side-effects of the flu shot that many don’t know about, why they happen, how rare they are, and how your health savings account (HSA), virtual doctor consultation, or health insurance plan may help you navigate them.
