Seventy-three of the 120 samples had nicotine content that veered from its packaging by as much as 88 percent less than the label to 840 percent more.
E-cigarettes are battery-powered devices that turn liquids, usually including nicotine, into an aerosol inhaled by the user.
They are promoted as a healthier alternative and an aid for quitting tobacco cigarettes, but there is debate over their safety. Health departments throughout Utah have started regulating e-cigarettes, mostly by trying to keep them away from minors.
More than a quarter of e-cigarettes listed as having nicotine (33 claimed to have none) did not have child-proof caps, the review found.
The health department says e-cigarettes are a poisoning threat to children; the Utah Poison Control Center had 131 calls related to e-cigarettes last year.
Salt Lake County Health Department managers launched the study because they're considering a new regulation requiring a license to make or sell e-cigarettes in the county.
Kathy Garrett, the department's tobacco prevention and cessation manager, said consumers should know how much nicotine they're getting.
"It's also a real concern for poison control center and emergency room staff, who don't know if the labeled amount of nicotine in a bottle a child has ingested is accurate," she said in the news release. "That makes this a life-or-death problem."