I had giardia once, and there was nothing occasional about the symptoms. I took what the doctor called "Flagyll" on the script and that got rid of the giardia. Then I drank about a gallon of buttermilk and ate about half a gallon of yogurt to replace everything else the meds got rid of too.

The symptoms from Giardia infection for me ranged from mild discomfort to full on distress, and though variable, were constantly present. The meds left me with a raw feeling inside, ravenously hungry.