once a week should be no problems at all, unless as others have said, you are taking wayyy over the maximum dosage.
For headaches you could try something like Excedrin, its acetominiophen + aspirin + caffeine
one pill is usually 250mg aceto, 250mg aspirin, 65mg caffeine.
These help me loads with migraine type headaches. Obviously though not to be taken at night due to the caffeine.