If you are a tobacco smoker, use of Acetaminophen can increase the risk of liver side effects. Immediately tell your doctor if you get severe abdominal pain, nausea, vomiting, or yellowing of the skin. Do not exceed 4 g acetaminophen/day in adults.
Captive iguanas often live to be 10-12 years old. There are reports of them having lived past 20 years in captivity. Only about a third of the iguanas sold in pet stores survive to maturity because of importation stress, improper diet, temperature and sunlight. In the wild, the number is even lower because the babies are finger-food for a number of jungle predators.
20 gallon tank is a good start. A well kept iguana grows between 2-3 inches a month (in the wild they go from 6â³ at hatch to ~42â³ by the end of their first year!) so it will grow out of that tank pretty fast. Many adult iguanas are housed in vinyl covered wire cages or home made wood and plastic panel enclosures.