Can topiramate cause nausea and lack of appetite?

Definitely, yes. Topiramate is a newer anticonvulsant that blocks voltage-gated sodium ion channels. Because it is not extensively metabolized in the liver, topiramate is being promoted as the successor to Gabapentin and is prescribed for a variety of pain disorders including the prophylaxis of migraine headache. Common side effects are dry mouth, loss of appetite, slow thinking, and trouble concentrating.