Patients should be alerted to the potential occurrence of allergic reactions and instructed to report them.
Particular caution should be exercised in patients with allergic diathesis or with bronchial asthma.
Patients should be watched for 30 minutes after drug administration and adrenalin should be kept ready for injection.
If allergic reactions occur, the drug should be withdrawn and the usual treatment with adrenalin, antihistamines and corticosteroids should be instituted.
To suppress or mitigate Jarisch-Herxheimer reactions (see Side Effects) prednisolone, 50 mg or an equivalent steroid, may be administered at the time of the first antibiotic dose. In patients with cardiovascular or meningovascular syphilis Jarisch-Herxheimer reactions can be prevented by prednisolone, 50 mg daily, or an equivalent steroid, for 1 to 2 weeks. In diabetics delayed absorption from the intramuscular depot should be remembered. During long-term treatment the blood count and renal function should be monitored. The potential overgrowth of resistant organisms should be kept in mind during long-term treatment. Patients developing secondary infections should be treated by suitable measures.
In patients treated for venereal diseases who are suspected of having co-existent syphilis dark-field examinations should be ordered prior to treatment and serologic tests should be obtained for at least 4 months. In patients with congenital syphilis the CSF should be examined prior to treatment.
Sustained severe diarrhea should prompt suspicion of antibiotic related pseudomembranous colitis (blood-streaked, mucoid, watery diarrhea dull, diffuse to colicky abdominal pain; fever and occasionally also tenesms). As this condition may be life-threatening, Sterile Penicillin G Benzathine should immediately be withdrawn and treatment guided by bacteriological studies (e. g. with oral vancomycin, 250 mg q. i. d.) should be instituted. Antiperistaltics are contraindicated.
To avoid sciatic nerve damage, infants and small children should not be injected into the upper outer quadrant of the buttock except in special cases, e. g. in the presence of extensive burns. Sterile Penicillin G Benzathine must not be injected subcutaneously, intravenously or intrathecally or instilled into body cavities.
Inadvertent subcutaneous injection may cause painful indurations. Pain is relieved by ice packs.
Inadvertent intravascular injection may cause Hoigne's syndrome (shock symptoms with a feeling of impending doom, confusion, hallucinations, at times also cyanosis, tachycardia and motor abnormalities, but no circulatory collapse). Attributable to microembolism of the suspension, these manifestations spontaneously disappear within 1 hour. In severe cases, patients should be given sedatives by injection.
Particularly in children, inadvertent intra-arterial injection may cause severe complications like vessel occlusion, thrombosis and gangrene. These are heralded by pale patches on the skin of the buttocks. If injected at high pressure, the injected fluid may be pushed upstream into the common iliac arteries, the aorta or the spinal arteries.