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Azathioprine is the generic name of a drug used to treat individuals with autoimmune conditions such as rheumatoid arthritis. An immunosuppressant, the drug works to slow the body's immune system, which can be useful in conditions where there is a malfunction within this system, but which also creates many of the side effects of azathioprine. As it slows the immune system, individuals taking it may find they are more prone to colds and infections, as well as developing certain types of cancer.
The drug acts by limiting the number of white blood cells produced by the immune system. These white blood cells are what fight infections in a healthy body, and in a person that has been compromised by an autoimmune disorder, these cells turn on healthy cells and tissues instead. This results in one of the major side effects of azathioprine, which is an inability to fight infections, specifically those that impact the body's gastrointestinal system.
With the gastrointestinal system compromised, an individual may be susceptible to bouts of vomiting and diarrhea. He or she may also feel nauseated. These side effects are usually temporary, and when the individual is taken off the drug, the immune system will return to its previous strength and once again be able to fight off these infections.
Other side effects of azathioprine are less common but more serious. An individual can feel lethargic and tired, or suffer from pain in a specific part of the stomach. Skin conditions such as the development of a rash or a yellow hue can also occur. Body aches and a loss of appetite can make an individual feel as though he or she is coming down with the flu, and a trip to a medical facility is often in order to determine whether it is the flu or side effects of the drug.
In rare cases, patients have developed liver toxicity as one of the side effects of azathioprine. Others have shown a susceptibility to developing types of skin or blood cancers. These side effects are rare.
For some, changing the dosage can remove the side effects of azathioprine. In other cases, it must be stopped altogether in order to eliminate serious side effects. As it can be transferred from a mother to her unborn baby or to the child through breast milk, the drug is usually not given to pregnant or nursing mothers because of the negative impacts it can have on a child. Azathioprine can also be prescribed for individuals who have recently had an organ transplant. Temporarily compromising the immune system with the drug can help deter the body's ability to reject the new organ.