The vaping devices were discovered to increase the blood pressure and heart rate of users.
And the study found that a condition known as arterial stiffness was three times greater in smokers using an e-cigarette containing nicotine than in one without nicotine.
While experts still say e-cigarettes are much healthier than tobacco cigarettes, the findings highlight that they are still not without risks.
Swedish scientists warned that regular vaping with nicotine liquids or being exposed to other people’s vapours could cause lasting damage to blood circulation. Stiffer arteries make it harder for the heart to pump blood round the body - which increases strain on the heart and increases the risk of damage to the heart muscle.
The condition is associated with high blood pressure, coronary artery disease, stroke, heart failure and atrial fibrillation.
Study leader Dr Magnus Lundback, from the Karolinska Institute in Stockholm, said: “The number of e-cigarette users has increased dramatically in the last few years and (the devices) have been marketed as ‘almost harmless’.
“However, the safety of e-cigarettes is debated, and a growing body of evidence is suggesting several adverse health effects.
“In this study we found there was a significant increase in heart rate and blood pressure in the volunteers who were exposed to e-cigarettes containing nicotine.”
The team recruited 15 young, healthy volunteers with an average age of 26. All were casual smokers on a maximum of 10 cigarettes a month who had not used e-cigarettes previously.
They used e-cigarettes with nicotine for 30 minutes on one day and devices without nicotine on the other day.
Researchers measured blood pressure, heart rate and arterial stiffness immediately after smoking and then two and four hours later, and found an immediate increase in arterial stiffness.
Lundback said: “The immediate increase in arterial stiffness that we saw is most likely attributed to nicotine.
“The increase was temporary. However, the same temporary effects on arterial stiffness have also been demonstrated after use of conventional cigarettes. Chronic exposure to both active and passive cigarette smoking causes a permanent increase in arterial stiffness.
“Therefore, we speculate that chronic exposure to e-cigarettes with nicotine may cause permanent effects on arterial stiffness in the long term.
“E-cigarette users should be aware of the potential dangers of this product, so they can decide whether to continue or quit based on scientific facts.”
Lundback criticised the industry for targeting non-smokers, including young people.
However, Professor Peter Hajek, director of the Tobacco Dependence Research Unit at Queen Mary University of London, said arterial stiffness was also true of other stimulants, such as caffeine.