evidence: The truth is, geckos are not harmful to humans and there is no evidence to suggest that they can transmit any diseases. Geckos may bite if they feel threatened or scared, but their teeth are too small to cause any real damage. In fact, most people report that geckos are gentle and docile creatures that make great pets. [...] So, are geckos harmful to humans? The answer is generally no, but it’s always important to use caution when interacting with these lizards. Geckos make great pets for people who are prepared to care for them properly, and they can be a fun addition to any home. [...] A. No, geckos are not known to carry any diseases that can harm humans. However, it is always important to wash your hands after handling any animal, including geckos, just to be safe.