Cannabis smoking has been linked with the development of male breast tissue, commonly known as "man boobs".
Gynecomastia, the medical term for man boobs, occurs when there is an imbalance in male and female hormones. Too much of the female hormone oestrogen, and too little testosterone can spark growth of breast tissue in men.
Writing on CNN, US plastic surgeon Dr Anthony Youn said that there is a good chance that marijuana makes man boobs worse, because animal studies have shown that it alters the body's balance of male and female hormones.
"In humans, the effects of marijuana on testosterone and oestrogen levels aren't as clear," he said.
"Lower testosterone levels have been reported in chronic marijuana users compared to nonusers, but not all studies support this."
Read more: How to get rid of man boobs for life
The link between marijuana and gynecomastia was first made in a 1972 study, but it has been difficult for researchers to investigate the link because marijuana is illegal in most places.
Now some states in America are legalising the drug, which Youn said would make it easier to reach firm conclusions.
"Although the association between marijuana and gynecomastia hasn't been conclusively proven, it appears very plausible," Dr Young wrote.
"For this reason, the majority of plastic surgeons I've consulted with routinely inquire with their gynecomastia patients about cannabis use and recommend they stop smoking pot immediately.”
Gynecomastia affects up to 30 percent of Australian males.
Sydney plastic surgeon Dr Scott Turner conducts male breast reduction surgery and said that while drug use is known to be linked with man boobs, in most cases the cause remains unknown.
"Male breast reduction or gynaecomastia surgery can contour the chest area to provide a more toned, athletic chest and increased self-confidence," Dr Turner's website says.
"The results of the procedure are significant and permanent."
But Dr Turner advises patients to attempt weight loss through diet and exercise before going under the knife.
"Obese men are not ideal gynaecomastia surgery candidates and should first attempt to correct their enlarged male breasts through weight loss and exercise," he wrote.
"Also, men who drink alcoholic beverages in excess, or regularly smoke marijuana or take anabolic steroids should stop the use of these substances, as they may have caused their enlarged breasts. It is prudent to discontinue the use of these substances for four to six months before considering gynaecomastia surgery."
Source: CNNhttp://edition.cnn.com/2013/12/05/health/youn-pot-moobs/ Author: Kimberly Gillan; Approving editor: Rory Kinsella