From the side of the central nervous system: agitation, a state of prostration, irritability, dizziness; rarely - depression, paranoia, fatigue, confusion, disorientation in time and space, hallucinations, nightmares, drowsiness, decreased visual acuity, pain and burning sensation in the eyes, photophobia, pain and a feeling of stuffiness in the ears, tinnitus.
From the digestive system: decreased appetite, diarrhea, constipation; rarely - dry mouth, flatulence, aggravation of hemorrhoid symptoms, erosive and ulcerative lesions of the gastrointestinal tract, increased activity of hepatic transaminases.
On the part of the urinary system: rarely - frequent or violated urination.
On the part of the reproductive system: delayed ejaculation, reduction of sexual potency; rarely - increased or decreased libido.
Dermatological reactions: rash; rarely - increased secretion of sebaceous glands, epidermophytic feet, skin changes, corresponding to the first stage of frostbite.
On the part of the respiratory system: rarely - hyperemia of the vessels of the nasal cavity, nosebleeds, rhinorrhea, sneezing, dryness in the throat, increased mucus, sinusitis, shortness of breath, tracheophone, cough, shortness of breath.
From the cardiovascular system: rarely - phlebitis, swelling, increased blood pressure, nonspecific changes in the cardiogram, tachycardia, a feeling of heat in the limbs, a sudden sensation of blood flow to the face.
Others: chills are possible; rarely - increase or loss of appetite, weight gain, pathological yawning, fever, pain in the groin, lymphadenopathy, lymphocytosis; describes one case of idiopathic thrombocytopenic purpura in a patient who appears to have been sensitized to naltrexone during the previous treatment.