Son holds his pee ALL DAY

My son is just 3 and we are on day 4 of underwear and potty training. He likes the underwear, wants the rewards we have ready for him, and will sit on the potty--he just won't go. And we've told him it's not ok to go in his pants, so he won't go in his pants, either. Yesterday he held everything from about 10am until 8pm.(Even during a 2 hour nap! The kid has amazing control!)  We finally gave up and put him in pajamas and a diaper around 8pm and he almost instantly soaked and filled the diaper. He just will not use the potty. And his holding everything in all day can't be healthy. He held his urine again today until about 5pm when he wet his pants after his daddy told him that if he wasn't ready to use the potty and his belly hurt, he could just go in his pants and we wouldn't be angry. I feel like we shouldn't go back to diapers, but I don't want him to hurt himself by holding his 'functions' for so long. What to do?

[Kevin Kennedy, Ph.D.]

He is very close to accomplishing toilet training, but he's obviously not quite there yet. It's OK to revert to the use of diapers, but it's also OK to stay on the present course - it's only been several days, not long at all. Also, ask him about his use (or non-use) of the potty, and see if there is some particular reluctance on his part that you might address. Continue with your use of rewards for successful use of the potty.