First Time Mommy
I switched from Similac Advance to Similac Sensitive and had great success with my daughter. I'm pretty sure that they're equivalent to the Enfamil and Enfamil Gentlease. My doctor just recommended trying everything available before going to soy. I'm not sure if either of those formulas are the soy version of Enfamil but based on what my pediatrician said, I would recommend trying the gentler version of Enfamil before going to the soy version!

rykell58
I personally used the Similac Sensitive for Fussiness & Gas this helped my son when he was constipated and had allot of gas. Your right when you say that you don't want to have to make the switch more than one time. You can also talk to your doctor about gas drops they make for baby's. I have never used them before but for some people they do work and then I have heard from others that they don't work at all, so I never tried them. It's worth a shot if your little one needs help. You could also ask your doctor about trying to offer your baby apple juice diluted of course to see if it will help him move things along, the only reason why I say ask is because he is so young. You could call the nurse online day or night to ask them questions. Good luck to you and your little love muffin.

Flymomma
When my daughter was born I gave her breast milk for about three weeks, weened her due to no sleep and started her on Similac Advanced w/Iron. This formula made what a mess of her little tummy but I didn't have a clue that it was the formula, I thought she was just fussy. She then would cry as if though she were in excruciating pain, she would pass gas and it was all gone. It hurt me terribly to watch her go through this but I didn't have a clue what to do. I saw the Enfamil LactoFree and started her on that. It took about three days for all of her symptoms to subside. She was good to go after the formula change. She didn't have any incidents at all, almost no spitting up, no more acid reflux and no more gas pains. She would sleep through the night and was a "normal" for lack of a better word, baby again. I had to keep her on Soy for about 4 months after the Formula phase, then I started her on cows milk. Her tummy would get incredibly bloated with the Similac because of the Lactose, after I started her in the Enfamil it went down considerably. I noticed the same when I started her on cows milk hence the Soy milk for 4 months. She is fine now and can drink either. Hope that helps.

Josephina is a Mommy!!!
My daughter is 7 weeks as well and has gas problems (not constipation though). We switched her from Enfamil Lipil to Enfamil gentlease Lipil for fussiness and gas. Her gas has improved, but still hasn't gone away. She's still pretty gassy... and thats with everything we have tried. The next move our doctor said it to try a soy based formula, so we may be switching again :( Every baby is different, it helped my daughter (alittle). You "may" have better results. Good Luck... I know how frustrating it can be to have a baby that is uncomfortable :(

Mama to a Lovie
my daughter had painful gas and a hard belly all the time before we switched to Gentlease. it worked for us! only had to switch her once.