Fenclofenac is a nonsteroidal anti-inflammatory drug (NSAID) previously used in rheumatism. It has mild immunosuppressive effects and may displace thyroid hormone from its binding protein. It can also cause lichen planus. Fenclofenac is a nonsteroidal anti-inflammatory drug (NSAID) previously used in rheumatism. It has mild immunosuppressive effects and may displace thyroid hormone from its binding protein. It can also cause lichen planus.