Why do I feel anxious and jittery after taking over-the-counter flu medicine?

Why do I feel anxious and jittery after taking over-the-counter flu medicine?

1. Introduction Feeling anxious and jittery after taking over-the-counter flu medicine is typically caused by active decongestant ingredients, such as pseudoephedrine or phenylephrine. These chemical compounds are central nervous system stimulants that mimic the effects of adrenaline, triggering the body’s physiological stress response. The resulting cardiovascular and neurological stimulation manifests physically as a rapid heart … Read more