Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Constipation and Diarrhea in Green Iguanas

Applicable to many other reptiles...

©1996, 2000 Melissa Kaplan




Iguanas are very much creatures of habit, of routine. If they eat daily, they will defecate daily. Digestion generally takes about 36-48 hours. The rate of digestion, as it relates to both the time of passage through the gut and to the efficiency of digestion, is a factor of body temperature, quantity, and quality of food. Efficiency relates to the breakdown and extraction of nutrients necessary to not only maintain basic body functions but to enable growth and reproduction.

The three things that most affect the digestive rate of passage through the gut and the efficacy of digestion (the extraction and metabolization of nutrients) are: nutritional density of the food, the ambient air temperatures, and activity levels. An iguana fed food poor in nutrition and low in fiber will take much longer to digest and will extract fewer nutrients from the food. Being fed such food in less-than-optimum environmental temperatures will result in still slower digestion and metabolization. The daily activity levels of such iguanas are low; there is less energy to spare as it is being directed towards keeping basic body functions (heart, respiration, etc.) going. Such igs are generally too cold to move around much and will be found staying either in the warmest place in the tank or in the coolest place, the latter a last ditch attempt to conserve energy as long as possible. Kept at proper temperatures, a poorly fed ig will also fail to thrive, typified by slow or stunted growth. These igs, too, may be less active, with most of their available energy going towards staying alive and maintaining what little growth they exhibit.

Feeding and heating your iguana properly and enabling it to engage in a regular daily activity routine will result in your having a green eating-and-pooping machine, with feces deposited regularly once a day (even twice a day during peak growing periods of spring and summer). 


An iguana who stops pooping daily while continuing to eat daily has a problem. The longer it goes without defecating, the more serious the situation. As wastes back up in the iguana's system, organ failure may occur.

First, check the enclosure temperatures. Constipation occurring during the winter is generally caused by the ambient enclosure temperatures dropping unnoticed by the owner as the overall temperatures in the home fall in response to colder winter weather. Adjusting the heating sources so as to provide the proper basking and thermal gradient temperatures is generally all the is require to restore regularity to the iguana.

Occasionally, bathing and massaging will be required. Bathe in warm (to the touch, about 80-85ºF/26.5-29ºC) water for 10-15 minutes. Then gently massage the iguana's belly, in smooth stokes from sternum to vent, for 5 minutes or so while it is still in the water. Let the iguana stay in the warm water (refreshing as necessary to maintain the proper temperatures) for at least another 10-15 minutes. The iguana should defecate within 24 hours if the blockage is due to being too cool, a very small piece or two of ingested substrate, or a very mild case of internal parasites.

If the blockage is due to heavy parasite infestation, a clump of ingested human or pet hair, or larger pieces or clumps of substrate (or other foreign objects), then the bathing or increased heat will have little to no effect and the iguana must be seen by a vet for further diagnostic work-up and treatment. I do not recommend the use of laxatives, especially without a veterinarian's supervision and thorough evaluation of the iguana's health and environment.

Severe metabolic bone disease and paralysis may also lead to constipation. Again, a vet visit and work-up will be required to determine the cause and initiate treatment.


Parasite infections, including worms and protozoans, may cause a loosening of the fecal mass to the point where it no longer holds its shape. The urates may be tinged reddish or rusty in the case of some protozoan infections. The feces of such iguanas often smell rank. When infected with Giardia, they may smell quite strongly, and strongly unpleasant.

Psychological upset may also cause temporary diarrhea as may a radical change in diet, or eating a food item that does not agree with the lizard's digestive system. Such temporary upsets may be successfully countered by administering a small amount of nonfat yogurt containing live cultures. Parasites cannot be so treated, however, and should not be treated with over-the-counter preparations found in pet stores.

A veterinarian is required to examine the feces to determine what organism is causing the problem and to prescribe the proper doses of the proper medication. Follow the directions for the initial and subsequent doses of medication and have the feces rechecked a couple of weeks after the last dose to determine whether an additional dose will be required. Information on collecting fecal samples and the types of tests performed may be found in the veterinary visit section of my Iguana Care, Feeding, and Socialization article.


 Related Articles

Green Iguana Feces and Urates

Substrates for Reptiles: Caveat emptor

Substrates - excerpt from master's thesis

Constipation in Reptiles

Use of Laxatives in Reptiles

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