Iguanas are popular reptiles because they grow fast, can be very easily tamed down and handled, and best of all, they are vegetarians. No need to provide insects or rodents, just a good variety of produce.
Like any reptile, they can carry salmonella and the CDC says they are not an appropriate pet for children 5 years and younger. They can also become quite large. Females can become egg bound so early spaying before they are egg bound and sick, is recommended. Males can become aggressive if not handled correctly and frequently when young.
Iguanas will suffer from painful metabolic bone disease if they are not provided optimum conditions including warmth, current dated uva/UVB lighting, calcium, and vitamin D supplementation.
Sick iguanas are tested for internal and external parasites, bloodwork and X-rays are often taken to make a diagnosis and develop a treatment plan.
Remember to always wash your hands after handling any animal, especially reptiles and amphibians. See information from the CDC about reptiles and contagious salmonella infections.