More than 15,000 people took part in the two-day EU Development Days in Brussels which atracted 5,000 development organisations.
Experts told the conference that large quantities drugs for cancer and depression as well as diet pills and vitamin supplements may be cheap counterfeits and can harm the health of people who use them.
The World Customs Organisation (WCO) said weak legislation in many countries had fuelled illict smuggling into Africa.
The WCO's counterfeiting and piracy expert Christophe Zimmerman claimed that the volume of goods made it impossible to track them all.
"Across the EU, we can only examine about 3% of all incoming goods but in Africa it doesn't even come to this.
"We can become more effective if we train customs officers in ports to focus on studying documents to identify forgeries."
He added: "We need a comprehensive framework for combatting fake medicines."
Ms Aline Plancon, who has responsibility for medical products in the Interpol's Counterfeiting and Pharmaceutical Crime Unit, said the law enforcement agency now monitors smuggling in up to 45 countries. She told the conference: "We need a multi-disciplinary approach. The problem didn't start today or yesterday, it goes back a very long time and we're talking about sophisticated gangs.
"There have been big improvements like in east Africa but for many police authorities this type of smuggling remains a low priority."
The counterfeit gangs mostly target drugs for cancer, depression and heart problems as well as diet pills and health supplements.
Ms Plancon added: "The counterfeit gangs are often ahead of the curve in terms of market trends and have the fake drugs ready to ship to meet a sudden demand.
"Packaging is so well copied that often the firms that manufacture the original goods find it difficult to tell the difference."
Official Margareth Ndomondu Sigonda of think-tank, New Economic Partnership for Africa's Development, called for a continent-wide medicines agency to combat fake medicines.
She claimed that that some 90% of medicines bought and sold in Africa could be fake.
The high-level annual EU Development Days event included contributions from 12 prime ministers, 24 heads of state and 44 government ministers and six Nobel Prize winners. Irish MEP Gay Mitchell, Alfred Hickey M'Sichili of Comhlámh and Alternatrade Project and Justin Kilcullen of Trocaire (in his capacity as President of CONCORD, the European NGO Confederation for Relief and Development) were among the speakers at the event. Irish Aid was also represented.