3 weeks post op and feel constantly thirsty. Is this a side effect of the surgery?

Ever since I've had surgery I always feel really thirsty. I drink so much that it makes me feel kinda sick. But a few hours later I'm extremely thirsty again. I only drink water and a lot of it! I have bad reactions to caffeine so I stay away from it. Is this a side affect of the surgery? Or my body healing? I have had no complications. Is this common to always feel dehydrated for awhile after surgery? Thank you