My Aleve Story

This question popped into my mind after I took an Aleve and my heart did something it wasn't supposed to do. It sped up or slowed down, either way it took my heart two hours to beat at a normal rate again. That got me to thinking, can the medicine in over the counter drugs kill you?

We perceive over the counter drugs as being safer than their prescription counter parts. If the FDA allows them to be sold without a prescription, then it must be safe. Let's not forget this is the same FDA that approved Fen-phen. My Aleve contains Naproxen sodium, which according to the label, may cause fatal stomach bleeding. So yes, my Aleve may kill me. But that's not the question. The question is why did my heart react to the medication like that? Here are the list of side effects not listed on the very smal label:

Constipation; diarrhea; dizziness; drowsiness; gas; headache; heartburn; nausea;
stomach upset; stuffy

Severe allergic reactions (rash; hives; itching;
trouble breathing; tightness in the chest; swelling of the mouth, face, lips, or
tongue; wheezing); bloody or black, tarry stools; change in the amount of urine
produced; chest pain; confusion; dark urine; depression; fainting; fast or
irregular heartbeat; fever, chills, or persistent sore throat; loss of appetite;
mental or mood changes; numbness of an arm or leg; one-sided weakness; pale
stools; red, swollen, blistered, or peeling skin; ringing in the ears; seizures;
severe headache or dizziness; severe or persistent stomach pain or nausea;
severe vomiting; shortness of breath; sudden or unexplained weight gain;
swelling of the hands, legs, or feet; unusual bruising or bleeding; unusual
joint or muscle pain; unusual tiredness or weakness; vision or speech changes;
vomit that looks like coffee grounds; yellowing of the skin or eyes.http://www.drugs.com/sfx/naproxen-side-effects.html

Noticed I highlighted the fast or irregular heartbeat. I also noticed that my vision was a bit weird, not anything widely noticeable, but I was unable to focus my eyes.So according to drugs.com, I experienced a severe allergic reaction. This is my first time experiencing such a reaction and this is my last time taking Aleve. Although it did what it is intended to do, the fact that it affected my heart scares me. The fact that I only took one scares me more.