Taking a selfie seems like a harmless act, but it caused serious negative health effects for one teenager.

Doctors at Dalhousie University in Canada discovered a young girl, who previously suffered from a seizure, experienced seizure-like episodes moments after she took a selfie, according to a case study. 

Read: Cannabidiol, A Compound In Marijuana, May Reduce Seizures In Rare Form Of Epilepsy

“This case suggests that taking ‘selfies’ may represent a new area of caution for those with photosensitive epilepsies,” the authors conclude in their paper, published in the medical journal Seizure.

Photosensitivity is rare and occurs among nearly 3 percent of people who have epilepsy, according to the Epilepsy Foundation. It can cause them to have seizures due to flashing or flickering lights, typically caused by natural light, strobe lights, television, and video games. However, in this particular case, it was caused from a phone’s camera flash.

In a three-day trial, researchers monitored the young girl’s electrical activity in her brain through a test known as EEG, or electroencephalogram. The test works by attaching small, flat discs to a person’s head, which pick up the electrical impulses that are constantly being sent from cell to cell as a means of communication. As she took selfies on her smartphone, the EEG test displayed the same type of brain acitivy examined during epileptic seizures.

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The doctors believe it may have occurred for one of two reasons: from the phone’s flash, or from the flashing red light used to eliminate red eye, Yahoo reported. Either way, more research needs to be conducted to confirm their findings.

Although “selfie epilepsy” is not a diagnosable condition, the researchers warn that those with photosensitive epilepsies should take extra caution with smartphones.

“There are reports of deaths and serious injury incurred while taking‘selfies’ and of frequent ‘selfies’ taken while driving motor vehicles,” the researchers wrote in their paper. “If a person with epilepsy were to have myoclonus induced by the flash of a “selfie” they could certainly sustain significant injury; particularly if they were already in a dangerous situation.”

Myoclonus is a quick, involuntary jerk caused by a sudden muscle contraction or relaxation.

People with photosensitive epilepsy often take anti-epileptic drugs to control their seizures. Another way to reduce the effect of photosensitivity is by wearing glasses with dark or polarizing lenses. 

See also: What Triggers A Seizure In Photosensitive Epilepsy? Science Discovers Why Still Photos Can Cause An Episode

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