People who smoke shisha regularly could be increasing the threat of heart disease, according to new research.
Shisha smoking, which is also called hookah or hubble-bubble smoking, is a way of smoking tobacco which is sometimes mixed with flavouring, through a bowl using a hose or tube which has become fashionable in Middle Eastern-style cafes.
New research by experts, supervised by Professor Brendan Madden of St George's, University of London, shows that heart rate, blood pressure and carbon monoxide levels rise significantly immediately after smoking shisha.
These physiological changes may lead to heart disease which in turn can lead to heart attacks.
The study was carried out in 2012 in six London shisha cafés where participants smoked for a period between 45 and 90 minutes. The same brand of tobacco and coal was used.
Those who had had smoked shisha in the previous 24 hours, who normally smoked cigarettes or who suffered from cardiorespiratory problems, were excluded from the study.
Professor Madden said: "Young people may be attracted to the social ambiance of these smoking cafes but they should also be aware that shisha smoking may well have an adverse effect on their health.
"There is minimum public awareness of the health risks of shisha smoking and a lack of scientific data.
"This research shows that there is an elevation in heart rate and mean blood pressure and carbon monoxide levels after smoking shisha and this may important in the development of cardio vascular disease.
"Further research is needed to verify the results of this research and to investigate the wider effects of smoking shisha.
"If future studies note the same effects of this research then the public should be made aware of the health effects of shisha smoking. This would include mandatory labelling of shisha tobacco packs and apparatus with 'smoking kills', which to date is not enforced at shisha cafés."
Researchers found that mean average arterial blood pressure increased from 96 mmHg to 108 mmHg, as did heart rate increased from 77 to 91 bpm and carbon monoxide also increased from an average of 3 to 35 parts per million.
The weak correlation between carbon monoxide levels and the other variables suggests that carbon monoxide levels had not contributed to their significant increase.
The research published in JRSM Open, the publication of the Journal of the Royal Society of Medicine.
Murtaza Kadhum, Ali Jaffery, Adnaan Haq, Jenny Bacon, and Brendan Madden, "Measuring the acute cardiovascular effects of shisha smoking: a cross-sectional study." JRSM Open June 2014 5: 2054270414531127, first published on June 5, 2014 DOI: 10.1177/2054270414531127