Adverse effects
The most common adverse effects are headache, hypothyroidism, cardiac conduction changes, gastrointestinal reactions (including cramps, nausea/vomiting and diarrhoea or constipation), gallstones, reduction of insulin release, hyperglycemia or sometimes hypoglycemia, and (usually transient) injection site reactions. Slow heart rate, skin reactions such as pruritus, hyperbilirubinemia, hypothyroidism, dizziness and dyspnoea are also fairly common (more than 1%). Rare side effects include acute anaphylactic reactions, pancreatitis and hepatitis.Some studies reported alopecia in those who were treated by octreotide. Rats which were treated by octreotide experienced erectile dysfunction in a 1998 study.A prolonged QT interval has been observed, but it is uncertain whether this is a reaction to the drug or the result of an existing illness. Interactions
Octreotide can reduce the intestinal reabsorption of ciclosporin, possibly making it necessary to increase the dose. People with diabetes mellitus might need less insulin or oral antidiabetics when treated with octreotide, as it inhibits glucagon secretion more strongly and for a longer time span than insulin secretion. The bioavailability of bromocriptine is increased;  besides being an antiparkinsonian, bromocriptine is also used for the treatment of acromegaly.
Pharmacology
Since octreotide resembles somatostatin in physiological activities, it can:

inhibit secretion of many hormones, such as gastrin, cholecystokinin, glucagon, growth hormone, insulin, secretin, pancreatic polypeptide, TSH, and vasoactive intestinal peptide,
reduce secretion of fluids by the intestine and pancreas,
reduce gastrointestinal motility and inhibit contraction of the gallbladder,
inhibit the action of certain hormones from the anterior pituitary,
cause vasoconstriction in the blood vessels, and
reduce portal vessel pressures in bleeding varices.It has also been shown to produce analgesic effects, most probably acting as a partial agonist at the mu opioid receptor. Pharmacokinetics
Octreotide is absorbed quickly and completely after subcutaneous application. Maximal plasma concentration is reached after 30 minutes. The elimination half-life is 100 minutes (1.7 hours) on average when applied subcutaneously; after intravenous injection, the substance is eliminated in two phases with half-lives of 10 and 90 minutes, respectively.