allergic to ritalin | ADHD Information

Hi, my good friend has a 5 year old boy who has recently been diagnosed with ADHD. He is delayed (functioning on the level of a three and a half year old) and recently started throwing a lot of tantrums.
His parents and doctors believe that it is necessary for him to be on medication, but he is very allergic to ritalin. They switched him to something called concerta but his tounge and faced swelled and they had to take him off it again.
I was wondering if anyone else has a child who is allergic to these medications, and if they tried any alternatives that the child wasnt allergic to?

My friend is so overwhelmed and frustrated, and I told her I would try and find out some things online.

Any responses would be appreciated!