How to prevent headaches after air travel<br>Try ibuprofen. Oftentimes, headaches that occur during or after flight are due to a sudden change in altitude. The painkiller ibuprofen may effectively prevent altitude related headaches before they begin.
Headaches that occur during or after flight are usually due to a sudden change in altitude.
The text says "Oftentimes, headaches that occur during or after flight are due to a sudden change in altitude." Often is not [necessarily] the same as usually, but the model thinks it is.
( z1 cause :ARG0 ( z2 change :ARG1 ( z3 altitude ) :manner ( z4 sudden ) ) :ARG1 ( z5 headache :time ( z6 or :op ( z7 fly ) :op ( z8 after :op z7 ) ) ) :mod ( z9 usual ) )