Tendinopathy is considered an overuse syndrome which usually results from excessive loading of the tendon during vigorous training activity. There are, however, various causes of this condition other than mechanical causes. This is a case report, in which a 42-year-old male suffered from bilateral plantar fasciitis after treatment with azithromycin for gastroenteritis. Azithromycin-induced tendinitis is a rare side effect, but it is important to know about this and other non-mechanical causes of tendinopathy, and to distinguish them from common mechanical causes in order to optimize treatment.