Sudi Hassan has received support from teachers and friends at Lilian Baylis school, in south London, for her investigation into khat, a narcotic plant that is illegal in many other countries but not in the UK.
She has interviewed dozens of Somalis about their experiences and was given the drug by a seller in Streatham, south London, last month while wearing her school uniform.
She was inspired to campaign against the use of khat after seeing friends and relatives become angry when they chewed it.
"My friend's dad would hit her and there were times when I was in the house when he shouted at her," she said. "The khat here seems different to the khat in Somalia, which was fresh from the fields. Here, I have heard it is being laced with cocaine."
Sudi grew up in Mogadishu, but was forced to flee Somalia after close relatives were killed by soldiers from a rival tribe. She only began speaking English in the summer of 2002 on arrival in the UK with her mother and her older brother and sister, who were all granted asylum.
Sudi has videotaped several of her interviews with Somali people in London who are affected by the drug.
She used camera equipment borrowed from Lilian Baylis's English department.
She now plans to set up a website and a helpline for users of the drug.
Andrew Marsh, deputy head at the school, helped to find funding so that she could print a series of "Somali Drug Helpline" T-shirts, which she has sold in aid of the campaign.
Khat can be bought in bunches for pound;4 from some greengrocers and from mafresh - meeting places where the drug is chewed.
The Home Office decided against making khat illegal in January on the basis of an assessment by the Advisory Council on the Misuse of Drugs.
It found that some khat-users were dependent and that there were anecdotal reports that they could become psychotic, but there was insufficient evidence to prove a causal link.
Gary Phillips, headteacher, said Sudi's achievements were astonishing.
"I think it is fantastic that Sudi has been able to investigate an issue that is close to her heart and has had a large impact on some members of her community," he said.
"I feel very proud of the staff who have helped give her the tools to produce such a staggering piece of research."