I personally think that it isnt that big of a problem right now. It will eventually develop into a problem soon. I have a step-son (he'll be 2 in june) who does not live with me, but who would be better off living with me(in my opinion). He sucks his two middle fingers. When he is with us, he is not allowed to do it. Sucking fingers/thumbs will cause teeth problems and also speech problems...especially if they talk with fingers/pasifiers in their mouths. About a month ago, during a weekend visit with my step-son, I changed his diaper and found worms in his poo. I immediately called the doctor that I have for my 3 year old son and she told me that she was not able to fit him in that day, but asked me if he sucked his fingers/thumb. When I told her "yes", she told me that a very good possible way for him to have gotten the worms is from crawling around on the floor and also from touching things with dirt/dust and then putting his bacteria infested fingers in his mouth. There are all sorts of bacteria that live under the fingernails and when injested can cause worms to live in the intestines. The doctor advised me to either take him to the ER to get treated or that I could go to my local Walgreens Pharmacy and pick up some Reese's Worm Treatment for pinworms. Because my step son's mother refuses to send his medicaid card with him when he visits, I chose to take him to the pharmacy and speak with the pharmacist about it. It only took one application of the medication and they were gone within 24 hours. A few of the ways that we tried to keep his fingers out of his mouth was to take a soft robe tie and we tied his hand losely behind his back or to his side. For bed time/nap time we put a pair of his socks on both of his hands to keep him from taking the socks off and his fingers ending up in his mouth. The only time that he was able to use his fingers was during bath time and during dinner time. Now, we do not have to use anything to keep his fingers out of his mouth. He has figured out that it is not allowed here and is fine with it all. He is still allowed to suck on his fingers at his mothers house. At the moment that I found out about the worms, I contacted his mother before I even contacted the doctor due to believing that she should be kept informed with what is going on with him, as I would expect from anyone who had my child for the weekend. She was told the main cause of the worm infestation, but still has not done anything to prevent a reinfestation. I hope that this information about pinworms does not scare you, but I wanted to share the possibile outcomes with sucking fingers. But hopefully using socks on both hands will help you when trying to wean her.