I know this can be a symptom of RA so it might be that rather than the Leflunomide causing it. I have it too. Mine is due to swelling and inflammation causing pressure on the nerves. I wear splints at night to help prevent it (given to me by the OT) and I find avoiding tight socks and shoes helps my feet. For me Crocs flip flops are heaven..........but my physio doesn't think they are good for the feet. Good luck with this.....and I hope they can get to the bottom of it and you'll find relief. Naomi.