evidence: Are geckos poisonous or venomous? Geckos are neither venomous nor poisonous. However, the Gila monster (Heloderma suspectum) and other large lizards, such as the Mexican beaded lizard (Heloderma horridum) and Komodo dragon (Varanus komodoensis), are venomous. That said, deaths due to bites from these big venomous lizards are extremely rare—dating back to 1939. [...] Some people think that geckos are dangerous because of the culture they belong to. Depending on their cultural background and upbringing, their superstitions regarding geckos can either be positive or negative. For example, geckos are considered symbols of good luck in Turkey but they are generally thought to be signs of bad omens in India.