Thousands of counterfeit and potentially defective condoms have been seized in West Yorkshire as part of a global crackdown on illicit medicines.
About 22,000 fake condoms were discovered at a property in Castleford by the UK's Medicines and Healthcare Products Regulatory Agency (MHRA).
Officers also discovered about 7,000 non-compliant syphilis test strips.
Danny Lee-Frost, of the MHRA, said using the condoms would be "playing Russian roulette" with your health.
The raid formed part of the Interpol co-ordinated Operation Pangea, an annual week of action tackling the online sale of counterfeit and illicit medical supplies and highlighting the dangers of buying them online.
Across the UK about four million doses of unlicensed medicines and 103,000 unapproved medical devices were seized.
Mr Lee-Frost said the address in Castleford was targeted after a shipment of 10,000 fake condoms from China and was intercepted en route to West Yorkshire.
He said MHRA officers discovered a large box of counterfeit condoms inside the property next to a second box full of jiffy bags "parcelled up and ready to go".
Referring to the syphilis test kits, he said: "We do not know if these work, we do not know if they are accurate.
"You are testing for a quite serious disease and if you get the wrong reading that's a life-changing decision that could affect not just you but lots of people."
Analysis: Jamie Coulson, BBC Look North
"The risks of buying counterfeit condoms are all too obvious.
"If they split or burst they will offer no protection against sexually transmitted diseases or pregnancy.
"Some copies may look genuine but previous seizures have included condoms where hand cream has been used for lubricant.
"Investigators said they were surprised by how many condoms they found at the house in Castleford and warned that many would be prone to bursting.
"The condoms will now be sent off for testing to establish if they are counterfeit or non-compliant with UK standards.
An MHRA spokesperson said: "Products such as these may not offer the correct level of protection you expect and could put your health at risk.
"Those involved in the illegal supply of medical products aren't interested in your health - they are only interested in your money."