Kiwi health officials have ordered the recall of six products sold to enhance men's sexual performance as they contain undeclared medicines.
The medicines are similar to active ingredients in prescription drugs such as Viagra and Cialis.
Acting health director-general Andrew Bridgman advised consumers to immediately stop taking the products, which are Shaguar, Signature Signergy, VIGRX (two types), VigRx, and VigRX Plus, citing "significant health risks" from their use.
Tadalafil is the active ingredient of Cialis, which is used to treat erectile dysfunction, while sildenafil is the active ingredient in Viagra, also an erectile dysfunction prescription drug.
Both taladalafil and sildenafil are known to interfere with some heart medications, and Medsafe said their use could be harmful and even fatal for some.
Hydroxyhomosildenafil and thiosildenafil were compounds similar in structure to sildenafil, whose safety and efficacy had not been established.
"Consumers should immediately stop taking these products and seek medical advice if they have felt unwell when taking any of these products or if they are also taking other medicines," Stuff.co.nz quoted Bridgman as saying.
The six products were being sold in New Zealand by retailers including "adult" shops, and over the Internet.
"Since July 2009, Medsafe has identified 45 ostensibly herbal supplements to enhance sexual performance which have been adulterated with similar prescription medicines," Bridgman stated.
Consumers should treat with "extreme caution" products claimed to boost sexual performance but offered for sale without a prescription.
Promoters, distributors, retailers and importers are required by law to be aware of all the active ingredients contained in their medicines and to seek approval before selling them.