E-cigarettes have long been touted as a safe alternative to tobacco smoke, but a recent study proves that's not the case.

Researchers said buyers of the electronic devices should beware of its unknown health effects of the electronic devices. They also noted that there is not enough evidence to support claims proposed e-cigarettes makers that it would help those who smoke cigarettes cut back.

"Despite the apparent optimism surrounding e-cigarettes and their purported therapeutic role in smoking cessation, there just simply is not enough evidence to suggest that consumers should use e-cigarettes for this purpose," allergist Andrew Nickels, lead author of the study and member of American College of Allergy, Asthma and Immunology (ACAAI), said in a statement.

Another cause for concern is that when people use e-cigarettes in public and still smoke regular cigarettes at home, they continue to expose children and asthma sufferers in the household to dangerous second hand smoke.

"Dual use of both e-cigarettes and regular cigarettes carries the risk of secondhand smoke exposure, causing worsening respiratory effects on children and asthma sufferers. It also promotes ongoing nicotine dependence," Chitra Dinakar, co-author of the study and ACAAI fellow and Professor of Pediatrics, said in a statement.

Researchers also noted that because e-cigarettes are fairly new, there could be other long-term health complications that have yet to be discovered. Results of long-term exposure to such substances are unknown. Due to the lack of production oversight, most consumers don't know what's in the e-cigarettes they buy. The U.S. Food and Drug Administration admits that the safety and efficacy of e-cigarettes hasn't been fully studied, and consumers have no way of knowing if e-cigarettes are safe for their intended use.

Researchers said inhaling irritants such as smoke and vapors has an impact on the lungs, whether it is mild or severe. And irritants can cause asthma attacks in some individuals. These attacks are responsible for some of the 4,000 asthma-related deaths per year.

The findings were recently published in the June issue of Annals of Allergy, Asthma & Immunology, the scientific journal of ACAAI.