WEDNESDAY, Oct. 17, 2012 (HealthDay News) -- People taking the popular antidepressant medications known as selective serotonin reuptake inhibitors (SSRIs) have a slightly higher risk of a hemorrhagic stroke, according to new research.
The increased risk for drugs such as Prozac (fluoxetine) and Paxil (paroxetine), however, still translates only to about a one in 10,000 rate of a hemorrhagic stroke for anyone taking an SSRI for a year.
And the raised risk tends to be strongest during the first few weeks and months after starting an SSRI, according to the study.
"Physicians should be aware of this association -- particularly in those with a history of brain hemorrhage or people taking anticoagulants like warfarin," said the study's lead author, Dr. Daniel Hackam, associate professor of medicine at the London Health Sciences Center of University Hospital in London, Ontario.
"But lower-risk people don't have to worry as much," he said. "The absolute increase in risk for the average person is about one in 10,000 cases per exposure to one of these drugs. If you're a long-term user, there's even less risk."
SSRIs are the most commonly used antidepressants, according to background information in the study. Besides Prozac and Paxil, other frequently prescribed SSRIs include Lexapro (escitalopram), Celexa (citalopram) and Zoloft (sertraline). These medications treat depression by changing levels of serotonin, a chemical neurotransmitter, in the brain.
SSRIs also inhibit platelet aggregation, which means they decrease the number of platelets in the red blood cells that stick together. In some people, this doesn't cause any problems. But in people whose blood is already thinner because of medical conditions or medications, it can cause serious problems, such as a hemorrhagic stroke.
A hemorrhagic stroke is caused by excess bleeding in the brain. This type of stroke is much less common than ischemic stroke, which is caused by a blood clot blocking a blood vessel in the brain.
For the study, published online Oct. 17 in the journal Neurology, the researchers reviewed 16 studies on antidepressant use and stroke. These studies had more than 500,000 participants combined.
They found that people taking SSRIs were about 50 percent more likely to have a hemorrhagic stroke. People who were taking oral anticoagulants (blood thinners) and SSRIs had an even higher risk of hemorrhagic stroke.
If someone needs to take SSRIs, Hackam said, this study shouldn't scare them away from their medication.
"The average young or middle-aged adult doesn't have to be worried," Hackam said. "People who have a higher risk of brain hemorrhage -- those with uncontrolled high blood pressure, on anticoagulants, alcoholics, elderly and people who have a history of a brain bleed -- should talk to their doctor about switching to an alternate class of medicine like bupropion (Wellbutrin) or tricyclic antidepressants."
There weren't enough people taking clopidogrel (Plavix) or aspirin for the researchers to assess the risk of these medications used in combination with SSRIs, although Hackam said it's plausible that someone taking SSRIs with these medications would likely have an increased risk too.
Hackam also pointed out that the risk of stroke decreases the longer someone takes SSRIs.
Another expert agreed that the study shouldn't cause alarm.
"The general public shouldn't be afraid of taking SSRIs," said Dr. Carolyn Drazinic, assistant professor in the department of psychiatry and the department of genetics and developmental biology at the University of Connecticut Health Center in Farmington, Conn.
"The risk of hemorrhagic stroke is very low," she added. "This study is more of a message to physicians to just think about this potential risk as they're starting someone on SSRIs."
Learn more about depression from the U.S. National Institute of Mental Health.