An FX option has "one-sided exposure" because only
the option holder pays for the potential of a favorable
outcome and the other party (the option writer) receives
payment to run the risk of unfavorable outcome.
Consequently, only the downside risk on the hedged item is
counterbalanced. Stated differently, any loss on the hedged
item can be offset by a gain on the hedging transaction. A
gain on the hedged transaction, however, cannot be offset by
a loss on the hedging transaction because the option holder
will let the option expire and thus not incur a loss on the
hedvinv transaction.