Flutamide Side Effects
Some side effects of flutamide may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.
For the Consumer
Applies to flutamide: oral capsule, oral tablet
Along with its needed effects, flutamide may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur while taking flutamide:More common
- Black, tarry stools
- bloody or cloudy urine
- continuing diarrhea
- continuing stomach pain
- difficult, burning, or painful urination
- frequent urge to urinate
- pale skin
- troubled breathing with exertion
- unusual bleeding or bruising
- unusual tiredness or weakness
- Blurred vision
- chest pain
- difficulty with breathing
- pounding in the ears
- shortness of breath
- slow or fast heartbeat
- sore throat
- sores, ulcers, or white spots on the lips or in the mouth
- swollen glands
- Abdominal or stomach pain
- clay-colored stools
- dark urine
- general tiredness and weakness
- light-colored stools
- loss of appetite
- nausea and vomiting
- unpleasant breath odor
- upper right abdominal pain
- vomiting of blood
- yellow eyes and skin
- Back, leg, or stomach pains
- bleeding gums
- blistering, peeling, or loosening of the skin
- bluish-colored lips, fingernails, or palms
- discoloration of the urine
- dizziness or lightheadedness
- flushing or redness of the skin
- general body swelling
- joint or muscle pain
- rapid heart rate
- red irritated eyes
- red skin lesions, often with a purple center
- unusually warm skin
Get emergency help immediately if any of the following symptoms of overdose occur while taking flutamide:Symptoms of overdose
- shakiness and unsteady walk
- tearing of the eyes
- unsteadiness, trembling, or other problems with muscle control or coordination
- weight loss
Some side effects of flutamide may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:More common
- Decreased interest in sexual intercourse
- feeling of warmth
- inability to have or keep an erection
- loss in sexual ability, desire, drive, or performance
- passing of gas
- redness of the face, neck, arms and occasionally, upper chest
- stomach pain, fullness, or discomfort
- sudden sweating
- swelling of the breasts or breast soreness in both females and males
- fear or nervousness
- mood or mental changes
For Healthcare Professionals
Applies to flutamide: oral capsule
In general, flutamide has been used concomitantly with LHRH agonists or after bilateral orchiectomy. Therefore, little data are available on the side effects of flutamide alone.
Nineteen cases of severe flutamide related hepatotoxicity were reported by the FDA in 1993. The flutamide related hepatitis developed 56 to 80 days after the beginning of therapy and was mainly cytolytic. Four of the cases involved massive hepatic necrosis with fatal outcomes. The mechanism of action was believed to be direct hepatotoxicity.
In a study of 1,091 patients with prostate cancer treated with flutamide and an LHRH agonist, four patients (0.36%) developed severe hepatotoxicity in the first four weeks of therapy. Serum aminotransferases increased more than four times normal values. Alkaline phosphatase increased more than six times normal values in one patient. Total bilirubin was elevated in two patients. Only two patients developed clinical manifestations, including fatigue, anorexia, weight loss, nausea, and vomiting. None of the remaining 1,089 patients had significant elevations in liver function tests although transient, mild elevations in AST and ALT occasionally occurred.
In most cases, discontinuation of flutamide results in resolution of symptoms.
A case of fatal liver complications has been reported where the drug was prescribed for an 18 year old woman for the treatment of minor acne and hirsutism. The risk of lethal hepatic complications makes the risk-benefit ratio unacceptable when flutamide is being considered to treat disorders such as polycystic ovaries, and especially for benign complaints such as alopecia, hirsutism, and acne.
Hepatic side effects have included elevations in serum transaminases as well as cases of cholestatic jaundice, hepatic necrosis, hepatic encephalopathy, and fatal hepatotoxicity.
Hematologic side effects have included anemia (6%), leukopenia (3%), and thrombocytopenia (1%). Flutamide has also been implicated in cases of methemoglobinemia, sulphemoglobinemia and neutropenia. In addition, eosinophilia has been reported in association with some cases of hepatotoxicity.
Nervous system side effects have been reported in less than 1% of patients and include drowsiness, dizziness, sedation, and confusion.
Renal side effects including renal failure (in association with severe hepatotoxicity) have been reported.
Cardiovascular side effects reported include hypertension (1%), thromboembolism, and edema.
Pseudoporphyria (blisters, increased skin fragility, and erosions in sun-exposed areas) was reported in a 68-year-old man being treated for prostate cancer with appropriate doses of flutamide and goserelin. The patient presented with skin fragility and blisters on the back of the hands. After replacing the flutamide with bicalutamide, the lesions healed.
Dermatologic side effects including rash (3%), alopecia, sweating, and cases of photosensitivity/photoallergy have been reported. One case of flutamide-induced pseudoporphyria has also been reported.
Endocrine side effects including hot flashes (29% to 63%), gynecomastia (up to 19%), fever, and breast tenderness (7%) have been reported.
Two female patients receiving flutamide for the treatment of bulimia nervosa noted decreased symptoms within a week after initiation of therapy. Both patients relapsed after the drug was later withdrawn.
Gastrointestinal side effects including mucositis, diarrhea, nausea, vomiting, abdominal pain, anorexia, and either weight loss or gain have been reported.
Musculoskeletal side effects including muscle cramps in up to 15% of patients have been reported.
Psychiatric side effects including depression, anxiety, and nervousness have been reported. One case report of mania has also been reported.
Genitourinary side effects including impotence and loss of libido have been reported.
Several studies have described a flutamide withdrawal syndrome in which significant reductions in prostate-specific antigen (PSA) levels are noted following the discontinuation of flutamide therapy in patients with hormone-refractory prostate cancer.
Several studies have evaluated the effect of concurrent discontinuation of flutamide and initiation of aminoglutethimide therapy in patients with hormone-refractory prostate cancer. In one study, serum PSA levels declined by more than 80% for more than four weeks in 14 out of 29 (48%) patients. Clinical improvement was also noted. Some authors propose prolonged flutamide therapy may result in the selective proliferation of cancer cell lines with androgen receptors which recognize hydroxyflutamide as an androgenic agonist. Additional research is needed to fully evaluate this phenomenon.
Other side effects have included flutamide withdrawal syndrome.
Respiratory side effects including one case of pneumonitis have been reported.
More flutamide resources
- flutamide MedFacts Consumer Leaflet (Wolters Kluwer)
- flutamide Concise Consumer Information (Cerner Multum)
- flutamide Advanced Consumer (Micromedex) - Includes Dosage Information
- Flutamide Prescribing Information (FDA)
- Flutamide Professional Patient Advice (Wolters Kluwer)
- Flutamide Monograph (AHFS DI)
- Eulexin Prescribing Information (FDA)
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