Some of the adverse reactions of taking<unk>  may include diarrhea, nausea, vomiting, loss of appetite, fatigue, stomach/abdominal pain, weakness, skin rash, darkening of the skin, and hair loss. Serious adverse reactions include mouth sores, fever, sore throat, easy bruising or bleeding, pinpoint red spots on the skin, yellowing of eyes or skin, dark urine, and painful or difficult urination. Other more serious side effects include black or tarry stools (melena), bloody stools, and bloody urine. Treatment is discontinued in up to 30% of patients due these effects but therapeutic drug monitoring of the biologically active metabolites, i.e. thiopurine nucleotides can help to optimize the efficacy and safety. Clinically, most hospitals resort to on-exchange LC-MS (liquid chromatography - mass spectrometry) but the newly developed approach of porous graphitic carbon based chromatography hyphenated with mass spectrometry appears superior with respect to patient care in this respect. Symptoms of allergic reaction to<unk>  include rash, itching, swelling, dizziness, trouble breathing, and inflammation of the pancreas. In some cases,<unk>  may suppress the production of blood cells, both white blood cells and red blood cells. It may be toxic to bone marrow. Quarterly blood counts are necessary for people on<unk> . People should stop taking the medication at least temporarily while considering alternate treatment if there is an unexplained, abnormally large drop in white blood cell count, or any other blood count. Toxicity of<unk>  can be linked to genetic polymorphisms in thiopurine S-methyltransferase (TPMT), nudix hydrolase 15 (NUDT15), and inosine triphosphate pyrophosphatase (ITPA). People with specific allele variants will require dose adjustments, especially for those with homozygous variant genotypes. Large differences of TPMT and NUDT15 among ethnicities in terms of variant allele frequency should be taken into consideration in clinical practice. Caucasian people with a variant allele of the ITPA gene, experience higher rates of febrile neuropenia than people of other ethnic groups, due to differences in allelic frequencies among ethnicities. Precautions<unk>  can lower the body's ability to fight off infection. Those taking it should get permission from a doctor to receive immunizations and vaccinations. It is also recommended that, while on the drug, one should avoid those having recently received oral polio vaccine. This drug was formerly not recommended during pregnancy and early evidence indicated pregnant women on the drug (or the related azathioprine) showed a seven-fold incidence of fetal abnormalities as well as a 20-fold increase in miscarriage. There were also anecdotal reports linking<unk>  with spontaneous abortion, leading to the US FDA rating both AZA and<unk>  as category D drugs. However, Davis et al. 1999 found<unk> , compared to methotrexate, was ineffective as a single-agent abortifacient; every woman in the<unk>  arm of the study had fetal cardiac activity at follow-up (two weeks later) and was given a suction abortion. A more recent, larger study, however, performed by the Cancers et Surrisque Associe aux Maladies inflamatoires intestinales En France (CESAME) indicated an overall rate of congenital malformations not significantly greater than the general population in France. The European Crohn's and Colitis Organisation (ECCO) concluded in a consensus paper in 2010 that while AZA and<unk>  have an FDA rating of D, new research in both animals and humans indicates that "thiopurines are safe and well tolerated during pregnancy."<unk>  causes changes to chromosomes in animals and humans, though a study in 1990 found, "while the carcinogenic potential of 6-MP cannot be precluded, it can be only very weak or marginal." Another study in 1999 noted an increased risk of developing leukemia when taking large doses of 6-MP with other cytotoxic drugs.
Mercaptopurine
Tioguanine
Thiopurine
Pomalidomide
Vincristine
Boroline
Thalidomide
Trimetrexate