Naltrexone Side Effects

Medically reviewed by Philip Thornton, DipPharm. Last updated on Jul 5, 2024.

For healthcare professionals

Applies to naltrexone: compounding powder, intramuscular powder for injection extended release, oral capsule, oral tablet.

Nervous system adverse events

• Very common (10% or more): Headache (25%), dizziness/syncope (13%)
• Common (1% to 10%): Somnolence/sedation
• Frequency not reported: Lethargy, cerebral arterial aneurysm, convulsions, disturbance in attention, dysgeusia, mental impairment, migraine, ischemic stroke, paresthesia^[Ref]

Psychiatric

• Very common (10% or more): Insomnia/sleep disorder (14%), anxiety (12%)
• Common (1% to 10%): Depression
• Uncommon (0.1% to 1%): Suicide attempt/ideation
• Frequency not reported: Irritability, abnormal dreams, agitation, alcohol withdrawal syndrome, euphoric mood, delirium, libido decreased^[Ref]

Gastrointestinal

• Very common (10% or more): Nausea (33%), vomiting NOS (14%), diarrhea (13%), abdominal pain (11%)
• Common (1% to 10%): Dry mouth, toothache
• Frequency not reported: Abdominal discomfort, colitis, constipation, flatulence, gastroesophageal reflux disease, gastrointestinal hemorrhage, hemorrhoids, pancreatitis acute, paralytic ileus^[Ref]

Hepatic

• Very common (10% or more): Alanine aminotransferase increased (13%), aspartate aminotransferase increased (10%)
• Common (1% to 10%): Gamma-glutamyltransferase increased
• Frequency not reported: Lymphadenopathy including cervical adenitis, white blood cell count increased, cholecystitis acute, cholelithiasis^[Ref]

Local

• 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]

Musculoskeletal

• 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]

Other

• Very common (10% or more): Asthenic conditions (23%)
• Frequency not reported: Chest pain, chest tightness, abortion missed^[Ref]

Cardiovascular

• Frequency not reported: Angina pectoris, angina unstable, atrial fibrillation, cardiac failure congestive, coronary artery atherosclerosis, myocardial infarction, palpitations, deep vein thrombosis^[Ref]

Respiratory

• Frequency not reported: Chronic obstructive pulmonary disease, dyspnea, pharyngolaryngeal pain, sinus congestion^[Ref]

Dermatologic

• Common (1% to 10%): Rash
• Frequency not reported: Face edema, night sweats, pruritus, sweating increased^[Ref]

Metabolic

• Very common (10% or more): Anorexia/appetite decreased NOS/appetite disorder NOS (14%)
• Frequency not reported: Weight decreased, weight increased, appetite increased, dehydration^[Ref]

Renal

• Very common (10% or more): Abnormal creatinine phosphokinase levels (17%)^[Ref]

Hematologic

• Frequency not reported: Eosinophil counts increased, decreased platelet count^[Ref]

Ocular

• Frequency not reported: Conjunctivitis, vision blurred^[Ref]

Hypersensitivity

• Frequency not reported: Hypersensitivity reaction (including angioneurotic edema and urticaria)
• Postmarketing reports: Anaphylaxis^[Ref]

Immunologic

• Very common (10% or more): Pharyngitis (11%)
• Common (1% to 10%): Nasopharyngitis
• Frequency not reported: Seasonal allergies^[Ref]

Frequently asked questions

• What is low dose naltrexone (LDN)?
• What happens if you drink alcohol while taking naltrexone?
• What to avoid when taking naltrexone?
• Should I take naltrexone in the morning or at night?
• Does naltrexone cause weight gain?
• Acamprosate vs naltrexone: How do they compare?
• How long does naltrexone take to work?
• How does naltrexone make you feel?
• What is the mechanism of action for naltrexone?

Further information

Naltrexone side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer