Police in 26 countries have collaborated on the raid and a total of 22 people have been arrested in connection with the crackdown on the global network.
The three suspects currently being held by police deny any involvement. A further two people were arrested but were later released without charge.
During the raid in capital, police seized a large amount of medication with an estimated value of 1 million kronor ($144,100).
The tablets appear to be known brands such as Viagra but tests have revealed some to be placebo pills while others have small or large amounts of effective substances.
”Some contain nothing and others pills contact either a fraction of the substances or ten times more than real prescription drugs,” said Cecilia Fant, criminal inspector from the National Criminal Investigation Department (Rikskriminalpolisen).
Over 750 illegal websites around the world which sell tampered medication have been identified and 72 have been shut down.
”There has been a growth in the number of illegal online drug stores and it is difficult to identify them,” Fant added. ”But we expect to arrest more people in Sweden in connection with this type of crime.”
Police are unable to estimate how many people have been affected in Sweden by buying the medication.
The pills are largely bought from China, India and Thailand and sold on at a huge profit via the internet.