Although no drugs have been approved by the U.S. Food and Drugs Administration (FDA) for the treatment of autism medication use in this group has become increasingly common with the global market estimated to be worth $2.2-$3.5bn. Selective serotonin reuptak inhibitors (SSRIs) account for 59% of this market but there is a dearth of evidence for their effectiveness. A team of researchers in the U.S., led by Bryan H. King from the University of Washington in Seattle studied the effectiveness of the SSRI citalopram in preventing the repetitive behaviour associated with autism and Asperger's syndrome. They studied 149 children between the ages of 5 and 17. 73 received citalopram and 76 a placebo. After 12 weeks there was no significant difference between the two groups and citalopram was more likely to cause side effects such as impulsiveness, decreased concentration, hyperactivity, diaorrhea, insomnia and dry or flaky skin.
King, Bryan H. ... [et al] - Lack of efficacy of citalopram in children with autism spectrum disorders and high levels of repetitive behaviour Archives of General Psychiatry June 2009, 66(6), 583-590