is an inhibitor of cyclin-dependent kinase 4/6 approved for the prevention of myelosuppression caused by chemotherapy. the drug is given before chemotherapy to protect bone marrow function. neutropenic enterocolitis due to immune system suppression, neutropenic enterocolitis (typhlitis) is a "life-threatening gastrointestinal complication of chemotherapy." typhlitis is an intestinal infection which may manifest itself through symptoms including nausea, vomiting, diarrhea, a distended abdomen, fever, chills, or abdominal pain and tenderness. typhlitis is a medical emergency. it has a very poor prognosis and is often fatal unless promptly recognized and aggressively treated. successful treatment hinges on early diagnosis provided by a high index of suspicion and the use of ct scanning, nonoperative treatment for uncomplicated cases, and sometimes elective right hemicolectomy to prevent recurrence. gastrointestinal distress nausea, vomiting, anorexia, diarrhea, abdominal cramps, and constipation are common side-effects of chemotherapeutic medications that kill fast-dividing cells. malnutrition and dehydration can result when the recipient does not eat or drink enough, or when the person vomits frequently, because of gastrointestinal damage. this can result in rapid weight loss, or occasionally in weight gain, if the person eats too much in an effort to allay nausea or heartburn. weight gain can also be caused by some steroid medications. these side-effects can frequently be reduced or eliminated with antiemetic drugs. low-certainty evidence also suggests that probiotics may have a preventative and treatment effect of diarrhoea related to chemotherapy alone and with radiotherapy. however, a high index of suspicion is appropriate, since diarrhoea and bloating are also symptoms of typhlitis, a very serious and potentially life-threatening medical emergency that requires immediate treatment. anemia anemia can be a combined outcome caused by myelosuppressive chemotherapy, and possible cancer-related causes such as bleeding, blood cell destruction (hemolysis), hereditary disease, kidney dysfunction, nutritional deficiencies or anemia of chronic disease. treatments to mitigate anemia include hormones to boost blood production (erythropoietin), iron supplements, and blood transfusions. myelosuppressive therapy can cause a tendency to bleed easily, leading to anemia. medications that kill rapidly dividing cells or blood cells can reduce the number of platelets in the blood, which can result in bruises and bleeding. extremely low platelet counts may be temporarily boosted through platelet transfusions and new drugs to increase platelet counts during chemotherapy are being developed. sometimes, chemotherapy treatments are postponed to allow platelet counts to recover. fatigue may be a consequence of the cancer or its treatment, and can last for months to years after treatment. one physiological cause of fatigue is anemia, which can be caused by chemotherapy, surgery, radiotherapy, primary and metastatic disease or nutritional depletion. aerobic exercise has been found to be beneficial in reducing fatigue in people with solid tumours. nausea and vomiting further information: chemotherapy-induced nausea and vomiting nausea and vomiting are two of the most feared cancer treatment-related side-effects for people with cancer and their families. in 1983, coates et al. found that people receiving chemotherapy ranked nausea and vomiting as the first and second most severe side-effects, respectively. up to 20% of people receiving highly emetogenic agents in this era postponed, or even refused potentially curative treatments. chemotherapy-induced nausea and vomiting (cinv) are common with many treatments and some forms of cancer. since the 1990s, several novel classes of antiemetics have been developed and commercialized, becoming a nearly universal standard in chemotherapy regimens, and helping to successfully manage these symptoms in many people. effective mediation of these unpleasant and sometimes debilitating symptoms results in increased quality of life for the recipient and more efficient treatment cycles, due to less stoppage of treatment due to better tolerance and better overall health. hair loss hair matting after few sessions of chemotherapy hair loss (alopecia) can be caused by chemotherapy that kills rapidly dividing cells; other medications may cause hair to thin. these are most often temporary effects: hair usually starts to regrow a few weeks after the last treatment, but sometimes with a change in color, texture, thickness or style. sometimes hair has a tendency to curl after regrowth, resulting in "chemo curls." severe hair loss occurs most often with drugs such as doxorubicin, daunorubicin, paclitaxel, docetaxel, cyclophosphamide, ifosfamide and etoposide. permanent thinning or hair loss can result from some standard chemotherapy regimens. chemotherapy induced hair loss occurs by a non-androgenic mechanism, and can manifest as alopecia totalis, telogen effluvium, or less often alopecia areata. it is usually associated with systemic treatment due to the high mitotic rate of hair follicles, and more reversible than androgenic hair loss, although permanent cases can occur. chemotherapy induces hair loss in women more often than men. scalp cooling offers a means of preventing both permanent and temporary hair loss; however, concerns about this method have been raised. secondary neoplasm development of secondary neoplasia after successful chemotherapy or radiotherapy treatment can occur. the most common secondary neoplasm is secondary acute myeloid leukemia, which develops primarily after treatment with alkylating agents or topoisomerase inhibitors. survivors of childhood cancer are more than 13 times as likely to get a secondary neoplasm during the 30 years after treatment than the general population. not all of this increase can be attributed to chemotherapy. infertility some types of chemotherapy are gonadotoxic and may cause infertility. chemotherapies with high risk include procarbazine and other alkylating drugs such as cyclophosphamide, ifosfamide, busulfan, melphalan, chlorambucil, and chlormethine. drugs with medium risk include doxorubicin and platinum analogs such as cisplatin and carboplatin. on the other hand, therapies with low risk of gonadotoxicity include plant derivatives such as vincristine and vinblastine, antibiotics such as bleomycin and dactinomycin, and antimetabolites such as methotrexate, mercaptopurine, and 5-fluorouracil. female infertility by chemotherapy appears to be secondary to premature ovarian failure by loss of primordial follicles. this loss is not necessarily a direct effect of the chemotherapeutic agents, but could be due to an increased rate of growth initiation to replace damaged developing follicles. people may choose between several methods of fertility preservation prior to chemotherapy, including cryopreservation of semen, ovarian tissue, oocytes, or embryos. as more than half of cancer patients are elderly, this adverse effect is only relevant for a minority of patients. a study in france between 1999 and 2011 came to the result that embryo freezing before administration of gonadotoxic agents to females caused a delay of treatment in 34% of cases, and a live birth in 27% of surviving cases who wanted to become pregnant, with the follow-up time varying between 1 and 13 years. potential protective or attenuating agents include gnrh analogs, where several studies have shown a protective effect in vivo in humans, but some studies show no such effect. sphingosine-1-phosphate (s1p) has shown similar effect, but its mechanism of inhibiting the sphingomyelin apoptotic pathway may also interfere with the apoptosis action of chemotherapy drugs. in chemotherapy as a conditioning regimen in hematopoietic stem cell transplantation, a study of people conditioned with cyclophosphamide alone for severe aplastic anemia came to the result that ovarian recovery occurred in all women younger than 26 years at time of transplantation, but only in five of 16 women older than 26 years. teratogenicity chemotherapy is teratogenic during pregnancy, especially during the first trimester, to the extent that abortion usually is recommended if pregnancy in this period is found during chemotherapy. second- and third-trimester exposure does not usually increase the teratogenic risk and adverse effects on cognitive development, but it may increase the risk of various complications of pregnancy and fetal myelosuppression. in males previously having undergone chemotherapy or radiotherapy, there appears to be no increase in genetic defects or congenital malformations in their children conceived after therapy. the use of assisted reproductive technologies and micromanipulation techniques might increase this risk. in females previously having undergone chemotherapy, miscarriage and congenital malformations are not increased in subsequent conceptions. however, when in vitro fertilization and embryo cryopreservation is practised between or shortly after treatment, possible genetic risks to the growing oocytes exist, and hence it has been recommended that the babies be screened. peripheral neuropathy further information: chemotherapy-induced peripheral neuropathy between 30 and 40 percent of people undergoing chemotherapy experience chemotherapy-induced peripheral neuropathy (cipn), a progressive, enduring, and often irreversible condition, causing pain, tingling, numbness and sensitivity to cold, beginning in the hands and feet and sometimes progressing to the arms and legs. chemotherapy drugs associated with cipn include thalidomide, epothilones, vinca alkaloids, taxanes, proteasome inhibitors, and the platinum-based drugs. whether cipn arises, and to what degree, is determined by the choice of drug, duration of use, the total amount consumed and whether the person already has peripheral neuropathy. though the symptoms are mainly sensory, in some cases motor nerves and the autonomic nervous system are affected. cipn often follows the first chemotherapy dose and increases in severity as treatment continues, but this progression usually levels off at completion of treatment. the platinum-based drugs are the exception; with these drugs, sensation may continue to deteriorate for several months after the end of treatment. some cipn appears to be irreversible. pain can often be managed with drug or other treatment but the numbness is usually resistant to treatment. cognitive impairment some people receiving chemotherapy report fatigue or non-specific neurocognitive problems, such as an inability to concentrate; this is sometimes called post-chemotherapy cognitive impairment, referred to as "chemo brain" in popular and social media. tumor lysis syndrome in particularly large tumors and cancers with high white cell counts, such as lymphomas, teratomas, and some leukemias, some people develop tumor lysis syndrome. the rapid breakdown of cancer cells causes the release of chemicals from the inside of the cells. following this, high levels of uric acid, potassium and phosphate are found in the blood. high levels of phosphate induce secondary hypoparathyroidism, resulting in low levels of calcium in the blood. this causes kidney damage and the high levels of potassium can cause cardiac arrhythmia. although prophylaxis is available and is often initiated in people with large tumors, this is a dangerous side-effect that can lead to death if left untreated.: 202 organ damage cardiotoxicity (heart damage) is especially prominent with the use of anthracycline drugs (doxorubicin, epirubicin, idarubicin, and liposomal doxorubicin). the cause of this is most likely due to the production of free radicals in the cell and subsequent dna damage. other chemotherapeutic agents that cause cardiotoxicity, but at a lower incidence, are cyclophosphamide, docetaxel and clofarabine. hepatotoxicity (liver damage) can be caused by many cytotoxic drugs. the susceptibility of an individual to liver damage can be altered by other factors such as the cancer itself, viral hepatitis, immunosuppression and nutritional deficiency. the liver damage can consist of damage to liver cells, hepatic sinusoidal syndrome (obstruction of the veins in the liver), cholestasis (where bile does not flow from the liver to the intestine) and liver fibrosis. nephrotoxicity (kidney damage) can be caused by tumor lysis syndrome and also due direct effects of drug clearance by the kidneys. different drugs will affect different parts of the kidney and the toxicity may be asymptomatic (only seen on blood or urine tests) or may cause acute kidney injury. ototoxicity (damage to the inner ear) is a common side effect of platinum based drugs that can produce symptoms such as dizziness and vertigo. children treated with platinum analogues have been found to be at risk for developing hearing loss. other side-effects less common side-effects include red skin (erythema), dry skin, damaged fingernails, a dry mouth (xerostomia), water retention, and sexual impotence. some medications can trigger allergic or pseudoallergic reactions. specific chemotherapeutic agents are associated with organ-specific toxicities, including cardiovascular disease (e.g., doxorubicin), interstitial lung disease (e.g., bleomycin) and occasionally secondary neoplasm (e.g., mopp therapy for hodgkin's disease). hand-foot syndrome is another side effect to cytotoxic chemotherapy. nutritional problems are also frequently seen in cancer patients at diagnosis and through chemotherapy treatment. research suggests that in children and young people undergoing cancer treatment, parenteral nutrition may help with this leading to weight gain and increased calorie and protein intake, when compared to enteral nutrition. limitations chemotherapy does not always work, and even when it is useful, it may not completely destroy the cancer. people frequently fail to understand its limitations. in one study of people who had been newly diagnosed with incurable, stage 4 cancer, more than two-thirds of people with lung cancer and more than four-fifths of people with colorectal cancer still believed that chemotherapy was likely to