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?