organic apple juice would be best. Make sure they are getting plenty of water during the day and if this is happening routinely, you may need to evaluate their diet. My daughter went through this a year ago and I needed to modify her diet. She was getting too much milk, yogurt, breads, not enough water and fruit, etc.
Miralax is not really the answer. Most of the time constipation is the cause of dietary problems or not having a balance and can be remedied at home. Miralax does not treat the underlying condition. It is also a drug and contains harsh chemicals that do not belong in the body, especially a 2 yr. old. My daughter was 1.5 when I went through this. We used no drugs and it took a month or more to figure out what I was doing wrong in feeding her and how to balance her out. We have not had any problems since. Apple juice, prunes when constipation is present and a problem. Does your child take any other drugs/medicines? They cause constipation because the chemicals are not meant for the body, so the body pulls water and tries to dilute it, if you notice constipation is a side effect on almost every single drug out there because of this reason.
Jarred Prunes and/or prune juice, you can get the jars in the baby food aisle at the grocery store for about 60 cents. Your LO will need a few jars over a couple of days to get thing moving....Is your LO eating enough fibre as in fruit and veg? Watch the amount of bread you are giving and processed/frozen/packaged food is especially hard for little kids to digest the more processed it is the harder it is for our bodies to break it down into energy for our bodies. I also find banana stop up my LO!!! But she does love them so....!
You can also call your dr if you are concerned this can be quite common in kids....i would avoid any medication unless your LO is diagnosed by a dr and really needs it