diziness from acetaminophen

When I take 1000mg acetaminophen for a headache, I get slightly dizzy and quite "spacey".
However, when I take Maximum Strength Pamprin for menustral-related headaches, I have no problems.  Pamprin contains (per dose) also 1000mg acetaminophen, with also 50mg pamabrom and 30mg pyrilamine maleate.
To me this does not seem logical, but it is how it is.  Is there a reasonable explanation for this?

[CCF-Neuro-M.D.-PW]

Its not clear why

Acetaminophen is thought to have some effect on local transmitter that mediate pain/sensations. An antihistamine like pyrilamine also works in a kind of similar fashion (on different transmitters). The two together may result in a slightly different effect/side effects that may explain the above. Other than that no other obvious explanation comes to mind. Be careful not to consume excessive acetminophen as in excess it can cause liver and kidney damage, and even death

[JoAnnaRF]

Just wanted to acknowledge the doctor's comment about the overuse of Acetominophen which is the main ingredient in Tylenol. Last year a close friend didn't wake up. She was rushed to the hospital where she was lucky enough to recieve a donor liver within a few days which saved her life! She now suffers from mild rejection symptoms and is in and out of the hospital when the symptoms worsen. Her liver failed due to taking too much Tylenol for back pain. She is a nurse who is 40 years old and alomost lost her life. So please be careful. Just because it's an OTC drug doesn't mean it can't be harmful if mis-used. And like the doc said, can even take your life.