GSK announced Thursday that it is voluntarily recalling its weight-loss product, alli, from US and Puerto Rico retail locations due to product-tampering concerns.

The drugmaker said in a statement that it is conducting an investigation with the FDA following inquiries from consumers about bottles of alli that contained “tablets and capsules that were not alli.”

“Safety is our first priority and we are asking retailers and pharmacies to remove all alli from their shelves immediately. We have posted a Consumer Alert on our website, www.myalli.com” President of GSK Consumer Healthcare North America Colin Mackenzie said in a statement.

Consumers who purchased the product are advised to call GSK at 800-671-2554 for a representative who will provide further instruction.