What are the side effects of taking citalopram with adderall xr?

There is a contraindiction between Adderall and Celexa, meaning they should NOT be taken together UNLESS you are under the supervision of a physician.

Celexa is in a class of drugs called SSRIs, or Selective Serotonin Reuptake Inhibitors. Serotonin is a type of chemical called a neurotransmitter and it functions to help pass signals between nerves. Celexa operates by keeping the nerves from taking the serotonin back up as quickly, so more stays between the nerves, helping to stimulate them.

Adderall is an amphetamine and effects the levels of several neurotransmitters. While its primary effect is on dopamine and norepinephrine, it also effects serotonin levels.

Combining these two medications is fairly common and while it's NOT likely, mixing the two can (rarely) lead to a severe, potentially fatal, condition called Serotonin Syndrome (sometimes called Serotonin Toxicity or Serotonin Storm).

The primary treatment for Serotonin Syndrome is stopping usage of the drugs that triggered it, followed by administration of a serotonin antagonist such as Periactin (cyproheptadine). Once it starts, it has to run its course. It can cause all sorts of conditions with tachycardia (fast heart rate) being the mildest, but it can also cause kidney failure, seizures, metabolic acidosis and other life threatening conditions.