ADHD Meds and Your Underweight Child

Dr. Cason,

Hello. I have a 10 year old little girl that is being treated for ADHD. She is currently on Vyvanse. The medication is working well for her. My problem is she is very underweight. She is 50 lbs. You can see every bone in her body! Protruding hips, ribs, and back bone. She is just scant of the 10% percentile on her growth chart so her pediatrician says not to worry unless she is 5% percentile. I could not even imagine what she would look like then!

We have tried to add other medications to increase appetite like Mirtazapine, but this is an extremely strong medication and knocks her out for a day. I don't want her to take that at 10. She eats high fat foods, (cheese, beans, ice cream, peanut butter, pasta etc.)I also give Pediasure once a day; she eats normally for her age but does not gain weight. I hear often from other people how skinny she looks too, so I don't think it's just me being too concerned.

She also seems to have a decreased immune system, she is sick often, and seems to catch everything going around. I am tired of being told not to worry when my child is always sick and is (not matter what the chart says) way under weight. Any suggestions?

Thanks so much... -K

Dear K,

Loss of appetite is a very common side effect of ADHD medications. ADHD meds can be very helpful for those kids where other options to treat ADHD meds haven’t been found to be helpful. Vyvanse (Lisdexamfetamine dimesylate) is a prodrug of dextroamphetamine which belongs to the group of medicines called central nervous system (CNS) stimulants. Stimulants are the most effective medications available for the treatment of ADHD as they increase alertness and concentration. Unfortunately the way that ADHD meds work also is the specific reason why your child is underweight. It suppresses appetite.

It sounds like you’re doing all the right things. Some people do add Remeron (Mirtazapine) because at low doses it acts as a antihistamine which increases sleepiness and stimulates appetite but there has been some concern over the use of anti-depressants and suicidal ideation in children. You definitely need to have someone experienced with ADHD
manage your child’s case.

Probably what will be most effective in helping your child gain weight is to give your daughter a
medication holiday if that’s feasible and okay with your doctor. You can give them a rest over the weekend and on vacations when increased attention won’t be as necessary for school or homework. I’ve also had some parents focus on feeding their children calorie rich foods as the medication wore off. This would be a time where the “No food before bedtime” rule could be bent.

I think your child is very thin as well. I charted her on a growth chart and my calculations showed a ten year old child who is 50 lbs is less than the 3rd percentile for her wt. Put another way, she is the average weight of a 7 year old. Given that she is on ADHD meds this may be the reason and if she otherwise looked healthy, it would be reasonable to not undergo other specific testing at this time. But if she’s sick a lot, she may be having other medical issues and would warrant a check up with her doctor. What labs need to be checked will be tailored to your child’s
specific situation and symptoms.

For now I would go back to your pediatrician and really talk with them. Bring up your concerns. Often when I have a family come in and express a deep concern, I will order labs even if I think everything is okay. I find it’s worth it to under go the tests for peace of mind. If the labs are normal you can assume it’s just the meds. You can then focus on giving her high calorie foods, medication holidays and returning for follow ups to monitor her growth. If your doctor isn’t comfortable managing the ADHD or poor weight gain, she can be referred to a behavioral specialist and a nutritionist for management.

Please see my other article on Tips on Mealtime and Your Underweight Child.

Best of luck to you,

Sheila Cason MD