My son's psychiatrist prescribes abilify 10 mg (once a day) and citalopram 20 mg (twice a day)?

I suggest you talk to both Drs. before he takes anything.

No! These Drs need to be aware of what the other is doing and work collectively, otherwise, conflicts and possible negative side effects may result.

You definitely need to get rid of the overlap. Some years ago my Psychiatrist asked me if if he could deal with the brain medication solely and my GP everything else (he asked for permission to contact my GP to ensure compliance).

It always gives me the horrors when I see some peoples medication list and they say this is from Dr A and this is from Dr B and I see Dr C for this... And none of these doctors know about the others or what they are prescribing. It is really quite dangerous.

Hi, if your son is going to continue to be seen by both his GP & Psychiatrist, then they need to build a professional relationship so that your son gets the treatment he needs safely. Combining these 3 medications can be very dangerous. Please contact both physicians asap. And please read through the link below:
https://www.drugs.com/interactions-check.php?drug_list=2543-0,679-0,233-109