Your body can develop tolerance to just about any drug, and tolerance (needing more to get the same effect) can be a sign of addiction. I'd suggest talking to your dr. about it.
--splitimage
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"I danced in the morning when the world was begun. I danced in the moon and the stars and the sun". From my favourite hymn.
"If you see the wonder in a fairy tale, you can take the future even if you fail." Abba