"It hasn't been approved for sale in New Zealand," he said.
He said the investigation would also include the Sunny's store in Browns Bay.
The spokesman said if it turned out the tablets were a restricted medicine, that meant they could be sold only by a pharmacist.
Before a medicine can be legally sold, distributed or advertised in New Zealand, the Minister of Health must give consent.
"But before consent is recommended, Medsafe must be satisfied that the product meets the safety, effectiveness and quality standards required," the spokesman said. He said while penalties could be applied by the ministry, in the case of first offenders it usually amounted to getting the store to remove all the goods.
But if the offending continued then stiffer penalties would be handed down.
Sunny's is part of a chain of variety stores that started out in Whangamata and now includes outlets in Browns Bay (Auckland), Whitianga, Paeroa, Mount Maunganui and Wanganui.
The Excedrin tablets, selling for $2.89 for eight tablets, are produced by Novartis Consumer Health Inc, a company based in New Jersey. They are sold in the US as an over-the-counter medicine.
The instructions on the Excedrin being sold here directs users to take two tablets at bedtime. The directions also say its use should be restricted to people over the age of 12.
The ingredients include 38mg of diphenhydramine, a common drug to help overcome sleeplessness.
A Chronicle reporter purchased two packets of Excedrin from Sunny's Avenue store last week. There were no warnings on the shelf where the tablets were displayed and the staff members did not question the purchase or the fact two packets were bought.
The Chronicle was alerted to the sale of Excedrin tablets when a Wanganui woman bought them at Sunny's store at 161 Victoria Ave. She bought one packet.
But concerned at the contents of the tablets, the woman brought them in to the Wanganui Chronicle.
According to Medsafe, diphenhydramine is a pharmacy-only drug found in medicines for adults and children over 6 years of age and generally used for anxiety or insomnia.
The tablets the woman purchased also contained acetominaphen, another name for paracetamol, which in most cases is a pharmacy or prescription-only medicine but in some cases can be sold generally.
