Lyprinol, the lipid extract of the green-lipped mussel (Perna canaliculus), is a readily and freely available agent with a putative anti-inflammatory impact. It has already found application as a complementary and supplementary treatment of osteoarthritis, rheumatoid arthritis, asthma, and cancer. So far no major side effects for Lyprinol have been reported, yet. Here, we present the case of a 76-year-old woman with acutely exacerbating abdominal pain and highly elevated liver transaminases while taking Lyprinol as a complementary treatment of polyarthrosis.