What are the side effects of octreotide 20 mg intramuscular long‑acting release (LAR)?

Side Effects of Octreotide 20 mg IM LAR

Octreotide LAR 20 mg IM is generally well tolerated, with gastrointestinal symptoms (diarrhea, abdominal discomfort, nausea) being the most common side effects, occurring in 34-61% of patients, though these typically resolve with continued treatment. 1

Common Side Effects (>10% of patients)

Gastrointestinal Effects

• Diarrhea, loose stools, nausea, and abdominal discomfort occur in 34-61% of acromegalic patients 1
• These symptoms are not dose-related and typically abate with continued treatment 2
• Only 2.6% of patients discontinue therapy due to GI symptoms 1
• Vomiting, flatulence, abnormal stools, abdominal distention, and constipation each occur in <10% 1
• Abdominal cramps and flatulence are common but usually resolve over time 2

Gallbladder Abnormalities

• Gallstones and biliary sludge develop in approximately 25% of patients 2
• Most cases are asymptomatic - only 4% develop biochemical evidence of cholestasis 2
• Routine ultrasound monitoring is NOT recommended unless patients develop symptoms 2
• Symptomatic gallbladder disease requiring intervention is rare 2

Glucose Metabolism Disturbances

• Hyperglycemia occurs in 16% of acromegalic patients 1
• Hypoglycemia occurs in 3% 1
• Glucose control usually improves, but rarely may worsen 2
• This occurs because octreotide inhibits both insulin and glucagon secretion 2, 3

Thyroid Effects

• Biochemical hypothyroidism occurs in 12% of acromegalic patients 1
• Goiter develops in 6% during therapy 1

Less Common Side Effects (1-10%)

Injection Site Reactions

• Pain at injection site: 7.7% 1
• Local skin irritation, hematoma, bruising, and edema 1

Cardiovascular Effects (in acromegalic patients)

• Sinus bradycardia (<50 bpm): 25% 1
• Conduction abnormalities: 10% 1
• Arrhythmias: 9% 1

Neurological

• Headache: 6% 1
• Dizziness: 5% 1

Other

• Fatigue and weakness (1-4%) 1
• Reversible hair loss (occasional), rarely alopecia 2

Rare but Serious Side Effects

Pancreatitis

• Reported but uncommon 1
• Monitor for symptoms 2

Severe Gastrointestinal Obstruction

• In rare instances, GI side effects may resemble acute intestinal obstruction with progressive abdominal distension, severe epigastric pain, abdominal tenderness, and guarding 1

Cardiac Events (1-4%)

• Chest pain, shortness of breath, thrombophlebitis, ischemia, congestive heart failure, hypertension, palpitations, tachycardia 1

Anaphylactoid Reactions

• Anaphylactic shock has been reported in several patients 1

Important Clinical Considerations

Routine monitoring should NOT include gallbladder ultrasound unless symptoms develop 2. This is a key practice point, as the 2014 Endocrine Society guidelines specifically recommend against routine screening despite the 25% incidence of gallstones.

The side effect profile is comparable between octreotide LAR and other long-acting somatostatin analogs 3, with similar rates of GI symptoms, gallbladder abnormalities, and glucose disturbances.

Most adverse effects are mild to moderate and transient, with only 2.6% of patients discontinuing therapy due to side effects 1. The long-term safety profile over treatment durations of up to 4 years shows progressive disease control without accumulation of serious adverse events 4.