Why is it that when you hit your head really hard, you always smell ammonia?

At least that is what I smell, and I have heard others say the same.What is the chemical reaction in the brain that causes this?
Answer:
To continue on what Val said (above), when you smell ammonia, it makes your eyes water. When you smack your head really hard, the pain can do the same. It is possible that your brain (along with those of others who experience the same phenomena) has formed a connection between the "smell" detector and the "eye watering" part, so that whenever the eye-watering occurs, the neurons for the ammonia smell fire off, too. My mom used to give me Coke for an upset stomach, and to this day, whenever I sip Coca Cola, I get an upset stomach - I think it is the same kind of thing.Hope this helps.

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you might be hitting a nerve that causes that.

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I think that only happens to you.

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the 4 concussions i have gotten in my life i didn't smell anything, or atleast didn't remember smelling anything.

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hold up i'll wack myself in the head and see if it's true...lol

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When people start to pass out we use capsules of ammonia to wake them up. perhaps you have had this done to you and your brain is telling you that it is a real smell. sounds like a remembrance smell and that the brain remembers it

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You've hit your head HARD, enough times to come to this conclusion?!?! See a doctor!!

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