"The substandard products referenced in this alert are unsafe and their use, especially in children, may result in serious injury or death," it said, adding that the toxic effects can include abdominal pain, vomiting, diarrhoea, inability to pass urine, headache, altered mental state, and acute kidney injury which may lead to death.
All batches of these products should be considered unsafe until they can be analysed by the relevant national regulatory authorities, the WHO said.
While these four products have been identified in The Gambia, it apprehended that they may have been distributed, through informal markets, to other countries or regions, and it "is important to detect and remove these substandard products from circulation to prevent harm to patients".