Naltrexone Side Effects
Medically reviewed by Drugs.com. Last updated on Apr 16, 2022.
Commonly reported side effects of naltrexone include: streptococcal pharyngitis, syncope, anxiety, arthralgia, arthritis, dizziness, drowsiness, fatigue, frequent headaches, headache, joint stiffness, nasopharyngitis, nausea, nervousness, obsessive compulsive disorder, panic attack, pharyngitis, posttraumatic stress disorder, sedated state, sinus headache, vomiting, induration at injection site, malaise, pain at injection site, and tenderness at injection site. Other side effects include: muscle cramps, muscle rigidity, muscle spasm, stiffness, depression, and twitching. See below for a comprehensive list of adverse effects.
For the Consumer
Applies to naltrexone: oral tablet
Other dosage forms:
Side effects requiring immediate medical attention
Along with its needed effects, naltrexone 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 naltrexone:
- Abdominal or stomach pain (severe)
- blurred vision, aching, burning, or swollen eyes
- chest pain
- discomfort while urinating or frequent urination
- hallucinations or seeing, hearing, or feeling things that are not there
- mental depression or other mood or mental changes
- ringing or buzzing in the ears
- shortness of breath
- swelling of the face, feet, or lower legs
- weight gain
Side effects not requiring immediate medical attention
Some side effects of naltrexone 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:
- Abdominal or stomach cramping or pain (mild or moderate)
- anxiety, nervousness, restlessness or trouble sleeping
- joint or muscle pain
- nausea or vomiting
- unusual tiredness
- cough, hoarseness, runny or stuffy nose, sinus problems, sneezing, or sore throat
- fast or pounding heartbeat
- increased thirst
- loss of appetite
- sexual problems in males
For Healthcare Professionals
Applies to naltrexone: compounding powder, intramuscular powder for injection extended release, oral tablet
Very common (10% or more): Headache (25%), dizziness/syncope (13%)
Common (1% to 10%): Somnolence/sedation
Very common (10% or more): Insomnia/sleep disorder (14%), anxiety (12%)
Common (1% to 10%): Depression
Uncommon (0.1% to 1%): Suicide attempt/ideation
Very common (10% or more): Nausea (33%), vomiting NOS (14%), diarrhea (13%), abdominal pain (11%)
Common (1% to 10%): Dry mouth, toothache
Very common (10% or more): Alanine aminotransferase increased (13%), aspartate aminotransferase increased (10%)
Common (1% to 10%): Gamma-glutamyltransferase increased
Very common (10% or more): Injection site tenderness (45%), injection site induration (35%), injection site pain (17%), other injection site reaction (primarily nodules, swelling) (15%), injection site pruritus (10%)
Common (1% to 10%): Injection site ecchymosis[Ref]
Very common (10% or more): Arthralgia/arthritis/joint stiffness (12%)
Common (1% to 10%): Back pain/stiffness, muscle cramps
Frequency not reported: Chills, joint stiffness, muscle spasms, myalgia, pain in limb[Ref]
Very common (10% or more): Asthenic conditions (23%)
Frequency not reported: Angina pectoris, angina unstable, atrial fibrillation, cardiac failure congestive, coronary artery atherosclerosis, myocardial infarction, palpitations, deep vein thrombosis[Ref]
Common (1% to 10%): Rash
Very common (10% or more): Anorexia/appetite decreased NOS/appetite disorder NOS (14%)
Very common (10% or more): Abnormal creatinine phosphokinase levels (17%)[Ref]
Frequency not reported: Eosinophil counts increased, decreased platelet count[Ref]
Very common (10% or more): Pharyngitis (11%)
Common (1% to 10%): Nasopharyngitis
Frequently asked questions
- What happens if you drink alcohol while taking naltrexone?
- Can you drink alcohol on Vivitrol or will you get sick?
- Does naltrexone cause weight gain?
- What to avoid when taking naltrexone?
- Should I take naltrexone in the morning or at night?
- What's the difference between naltrexone and naloxone?
- How long does naltrexone take to work?
- How does naltrexone make you feel?
- How long does Vivitrol last in your system?
- What happens if you take opiates while on Vivitrol?
- Does this drug make you sleepy?
- Does this drug block endorphins?
- Is naltrexone a controlled substance?
- How and where is the Vivitrol injection given?
More about naltrexone
- Drug interactions
- Dosage information
- During pregnancy or Breastfeeding
- Reviews (522)
- Patient tips
- Drug images
- Compare alternatives
- Pricing & coupons
- Drug class: antidotes
- Drug Information
- Naltrexone injection
- Naltrexone (Advanced Reading)
- Naltrexone Intramuscular (Advanced Reading)
- Naltrexone Tablets
Related treatment guides
1. "Product Information. Vivitrol (naltrexone)." Alkermes, Inc, Cambridge, MA.
2. "Product Information. Naltrexone Hydrochloride (naltrexone)." Accord Biopharma Inc, Durham, NC.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Some side effects may not be reported. You may report them to the FDA.