Naltrexone Side Effects
Please note - some side effects for Naltrexone may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).
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For the consumer For the professional
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Side Effects of Naltrexone - for the consumer
Naltrexone
All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Naltrexone:
Seek medical attention right away if any of these SEVERE side effects occur when using Naltrexone:Anxiety; appetite loss; chills; constipation; delayed ejaculation; diarrhea; dizziness; drowsiness; feeling down; headache; increased energy; increased thirst; irritability; joint and muscle pain; low energy; nausea; nervousness; sleeplessness; stomach pain/cramps; vomiting.
TopSevere allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); abdominal or stomach pain; cramping; dark urine; depression; suicidal thoughts or behaviors; unusual tiredness or weakness; vomiting; white bowel movements; yellowing of the skin or eyes.
For the professional
Naltrexone
During two randomized, double-blind placebo-controlled 12 week trials to evaluate the efficacy of Naltrexone as an adjunctive treatment of alcohol dependence, most patients tolerated Naltrexone well. In these studies, a total of 93 patients received Naltrexone hydrochloride at a dose of 50 mg once daily. Five of these patients discontinued Naltrexone because of nausea. No serious adverse events were reported during these two trials.
While extensive clinical studies evaluating the use of Naltrexone in detoxified, formerly opioid-dependent individuals failed to identify any single, serious untoward risk of Naltrexone use, placebo-controlled studies employing up to five-fold higher doses of Naltrexone hydrochloride (up to 300 mg per day) than that recommended for use in opiate receptor blockade have shown that Naltrexone causes hepatocellular injury in a substantial proportion of patients exposed at higher doses.
Aside from this finding, and the risk of precipitated opioid withdrawal, available evidence does not incriminate Naltrexone, used at any dose, as a cause of any other serious adverse reaction for the patient who is“opioid free.” It is critical to recognize that Naltrexone can precipitate or exacerbate abstinence signs and symptoms in any individual who is not completely free of exogenous opioids.
Patients with addictive disorders, especially opioid addiction, are at risk for multiple numerous adverse events and abnormal laboratory findings, including liver function abnormalities. Data from both controlled and observational studies suggest that these abnormalities, other than the dose-related hepatotoxicity described above, are not related to the use of Naltrexone.
Among opioid free individuals, Naltrexone administration at the recommended dose has not been associated with a predictable profile of serious adverse or untoward events. However, as mentioned above, among individuals using opioids, Naltrexone may cause serious withdrawal reactions.
Reported Adverse Events:
Naltrexone has not been shown to cause significant increases in complaints in placebo-controlled trials in patients known to be free of opioids for more than 7 to 10 days. Studies in alcoholic populations and in volunteers in clinical pharmacology studies have suggested that a small fraction of patients may experience an opioid withdrawal-like symptom complex consisting of tearfulness, mild nausea, abdominal cramps, restlessness, bone or joint pain, myalgia, and nasal symptoms. This may represent the unmasking of occult opioid use, or it may represent symptoms attributable to Naltrexone. A number of alternative dosing patterns have been recommended to try to reduce the frequency of these complaints.
Alcoholism:
In an open label safety study with approximately 570 individuals with alcoholism receiving Naltrexone, the following new-onset adverse reactions occurred in 2% or more of the patients: nausea (10%), headache (7%), dizziness (4%), nervousness (4%), fatigue (4%), insomnia (3%), vomiting (3%), anxiety (2%) and somnolence (2%).
Depression, suicidal ideation, and suicidal attempts have been reported in all groups when comparing Naltrexone, placebo, or controls undergoing treatment for alcoholism.
| Naltrexone | Placebo | |
| Depression | 0 to 15% | 0 to 17% |
| Suicide Attempt/Ideation 0 to 1% | 0 to 3% |
Although no causal relationship with Naltrexone is suspected, physicians should be aware that treatment with Naltrexone does not reduce the risk of suicide in these patients.
Opioid Addiction:
The following adverse reactions have been reported both at baseline and during the Naltrexone clinical trials in opioid addiction at an incidence rate of more than 10%:
Difficulty sleeping, anxiety, nervousness, abdominal pain/cramps, nausea and/or vomiting, low energy, joint and muscle pain, and headache.
The incidence was less than 10% for:
Loss of appetite, diarrhea, constipation, increased thirst, increased energy, feeling down, irritability, dizziness, skin rash, delayed ejaculation, decreased potency, and chills.
The following events occurred in less than 1% of subjects:
Respiratory: nasal congestion, itching, rhinorrhea, sneezing, sore throat, excess mucus or phlegm, sinus trouble, heavy breathing, hoarseness, cough, shortness of breath.
Cardiovascular: nose bleeds, phlebitis, edema, increased blood pressure, non-specific ECG changes, palpitations, tachycardia.
Gastrointestinal: excessive gas, hemorrhoids, diarrhea, ulcer.
Musculoskeletal: painful shoulders, legs or knees; tremors, twitching.
Genitourinary: increased frequency of, or discomfort during, urination; increased or decreased sexual interest.
Dermatologic: oily skin, pruritus, acne, athlete's foot, cold sores, alopecia.
Psychiatric: depression, paranoia, fatigue, restlessness, confusion, disorientation, hallucinations, nightmares, bad dreams.
Special senses: eyes-blurred, burning, light sensitive, swollen, aching, strained; ears-“clogged”, aching, tinnitus.
General: increased appetite, weight loss, weight gain, yawning, somnolence, fever, dry mouth, head“pounding”, inguinal pain, swollen glands,“side” pains, cold feet,“hot spells.”
Post-marketing Experience: Data collected from post-marketing use of Naltrexone show that most events usually occur early in the course of drug therapy and are transient. It is not always possible to distinguish these occurrences from those signs and symptoms that may result from a withdrawal syndrome. Events that have been reported include anorexia, asthenia, chest pain, fatigue, headache, hot flashes, malaise, changes in blood pressure, agitation, dizziness, hyperkinesia, nausea, vomiting, tremor, abdominal pain, diarrhea, elevations in liver enzymes or bilirubin, hepatic function abnormalities or hepatitis, palpitations, myalgia, anxiety, confusion, euphoria, hallucinations, insomnia, nervousness, somnolence, abnormal thinking, dyspnea, rash, increased sweating, and vision abnormalities.
Depression, suicide, attempted suicide and suicidal ideation have been reported in the post-marketing experience with Naltrexone used in the treatment of opioid dependence. No causal relationship has been demonstrated. In the literature, endogenous opioids have been theorized to contribute to a variety of conditions. In some individuals the use of opioid antagonists has been associated with a change in baseline levels of some hypothalamic, pituitary, adrenal, or gonadal hormones. The clinical significance of such changes is not fully understood.
Adverse events, including withdrawal symptoms and death, have been reported with the use of Naltrexone in ultra rapid opiate detoxification programs. The cause of death in these cases is not known.
Laboratory Tests: With the exception of liver test abnormalities, results of laboratory tests, like adverse reaction reports, have not shown consistent patterns of abnormalities that can be attributed to treatment with Naltrexone.
Idiopathic thrombocytopenic purpura was reported in one patient who may have been sensitized to Naltrexone in a previous course of treatment with Naltrexone. The condition cleared without sequelae after discontinuation of Naltrexone and corticosteroid treatment.
TopMore resources:
Naltrexone - Includes detailed dosage instructions.
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