The authorities in Nigeria say they are concerned that people are buying large quantities of hydroxychloroquine - a drug touted, but not yet proven, to help cure Covid-19.
Head of the Presidential Task Force on Covid-19, Boss Mustapha, said the government had through its surveillance system, received reports of abuse of the anti-malaria drug.
“We wish to reiterate that this drug has not been certified for use in treating Covid-19 in Nigeria by the relevant health and pharmaceutical authorities.
"Self-medication of any kind is fraught with the danger of increasing risks of avoidable casualties," he said.
Chloroquine has been phased out as a front-line anti-malarial drug in Nigeria, where malaria is endemic, following widespread resistance to it.
However, the drug has been approved for clinical trials in the treatment of coronavirus in Lagos state, Nigeria's epicentre for the virus which has so far recorded more than 3,000 cases.
Chloroquine has not yet been shown to be safe and effective in the prevention or treatment of coronavirus and the World Health Organization has warned that individuals who self-medicate risk causing themselves serious harm.
In late March, there were reports of people in Nigeria overdosing on the drug with some ending up in hospital, after US President Donald Trump touted hydroxychloroquine as a possible treatment for Covid-19.
This week, Mr Trump said he was taking hydroxychloroquine as a preventative measure against Covid-19, although scientists have warned about side effects.
Nigeria has reported 4,898 active cases of Covid-19 with 211 deaths and 1,907 recoveries.