One in seven Nigerians uses drugs, more than twice the global average, according to the country's first major national drug-use survey published on Tuesday.
The survey, conducted by the Nigerian government, the European Union and the United Nations Office on Drugs and Crime(UNODC), said an estimated 14.4 percent of Nigerians uses drugs. That is more than twice the global average of 5.6 percent.
It based its findings on data collected from nearly 50,000 respondents.
In Nigeria, that 14.4-percent figure translates to 14.3 million people aged 15 to 64 using drugs other than alcohol and tobacco last year, said the survey.
"Some of the findings of the survey presented today are striking and alarming," said Nigeria's health minister, Osagie Ehanire.
They require "concerted efforts to mitigate the negative consequences of this rising menace on the health, socio-economic and security of our nation". A new drug-control masterplan was being formulated to tackle the problem, he added.
The report revealed for the first time the extent of drug use in Africa's most populous nation.
It said that 4.6 million people -- 4.7 percent of the population -- used prescription painkillers such as tramadol and cough syrups for non-medical purposes last year.
This abuse, responsible for most of the negative health impacts of drugs, led to Nigeria banning codeine-based cough syrups last year because of concern at the spiralling rates of abuse.
The levels of consumption in Nigeria placed it among the countries with "highest estimates of non-medical opioid use globally", the report said.
Many of Nigeria's drug users are in the restive northeast, which has suffered from the Boko Haram insurgency for almost a decade.
But the highest rate of drug use is in the southwest, where just over one in five (22.4 percent) of 15-64 year olds used drugs last year, the report said.
In Lagos, Nigeria's sprawling megacity where poverty and unemployment is increasing, drug use was even higher, at 33 percent.
In Nigeria, as in the rest of the world, the most abused drug was cannabis, according to the report.