Over 600,000 doses of illegal medicines were seized last year.
The figure is a significant reduction on 2017 figures when almost 950,000 units were uncovered.
Of the illegal drugs detained last year, over a third were sedatives, erectile dysfunction tablets made up 18 percent and anabolic steroids accounted for 16 percent.
10 cases were prosecuted and 14 formal cautions were issued.
The Health Products Regulatory Authority is warning people they are putting their health at significant risk by buying medicines from unverified and unregulated sources.
