Smoking cannabis may cause early puberty and stunted growth in boys, research has shown.

Scientists studied hormones in the blood of 437 boys, including 217 who habitually smoked cannabis before reached puberty.

They found that levels of puberty-related hormones such as testosterone were raised in the drug users, who also had reduced levels of growth hormones.

By the age of 20, non-cannabis smokers were on average four kilograms heavier and 11.6cm taller than smokers.

The researchers also found that levels of the stress hormone cortisol were significantly higher in saliva samples from boys taking cannabis.

The scientists, led by Syed Rizvi from the Pir Mehr Ali Shah Agriculture University in Rawalpindi, Pakistan, wrote in a study presented at the European Congress of Endocrinology’s annual meeting in Dublin: “Marijuana use may provoke stress responses resulting in stimulation of pubertal development and suppression of growth rate.”

It is estimated that 80.5 million Europeans have taken cannabis at least once in their life.

According to the latest report from the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) the highest prevalence of marijuana use is among male 15 to 24-year-olds.

Rizvi said: “Early puberty is associated with younger age onset of drinking and smoking, and early matures have higher levels of substance abuse because they enter the risk period at an early level of emotional maturity.”