Can pharmaceutical companies sell over-the-counter drugs without invoicing?

Of course. According to the relevant information, it is not illegal for small and micro enterprises not to issue invoices in their daily sales, but it is illegal if the other buyer requests to issue invoices without issuing them. After small and micro enterprises sell goods or provide services, they must issue invoices as long as the other party needs to issue invoices. If the other party doesn't need an invoice, it doesn't need to issue an invoice, but it must be included in the business income of the enterprise and declared and paid taxes according to the regulations.