fatigue, diarrhea, unusual dreams, trouble sleeping, depression, and vision problems. β-blockers, including metoprolol, reduce salivary flow via inhibition of the direct sympathetic innervation of the salivary glands. Metoprolol may also cause the hands and feet to feel cold. Due to the high penetration across the blood–brain barrier, lipophilic beta blockers such as propranolol and metoprolol are more likely than other less lipophilic beta blockers to cause sleep disturbances such as insomnia, vivid dreams and nightmares. Serious side effects that are advised to be reported immediately include symptoms of bradycardia (resting heart rate slower than 60 beats per minute), persistent symptoms of dizziness, fainting and unusual fatigue, bluish discoloration of the fingers and toes and/or lips, numbness/tingling/swelling of the hands or feet, sexual dysfunction, erectile dysfunction, hair loss, mental/mood changes, depression, breathing difficulty, cough, dyslipidemia and increased thirst. Consuming alcohol while taking metoprolol may cause mild body rashes and is not advised. Precautions It is well documented that metoprolol reduces long-term mortality and hospitalisation due to worsening heart failure. A meta-analysis further supports reduced incidence of heart failure worsening in patients treated with beta-blockers compared to placebo. However, in some circumstances, particularly when initiating metoprolol in patients with more symptomatic disease, an increased prevalence of hospitalisation and mortality has been reported within the first two months of starting. Patients should monitor for swelling of extremities, fatigue, and shortness of breath. This medicine may cause changes in blood sugar levels or cover up signs of low blood sugar, such as a rapid pulse rate. It also may cause some people to become less alert than they are normally, making it dangerous for them to drive or use machines. Greater care is required with use in those with liver problems or asthma. Stopping this drug should be done slowly to decrease the risk of further health problems. Pregnancy and breastfeeding Risk for the fetus has not been ruled out, per being rated pregnancy category C in the United States. Metoprolol is category C in Australia, meaning that it may be suspected of causing harmful effects on the human fetus (but no malformations). It appears to be safe in breastfeeding. Overdose Excessive doses of metoprolol can cause severe hypotension, bradycardia, metabolic acidosis, seizures, and cardiorespiratory arrest. Blood or plasma concentrations may be measured to confirm a diagnosis of overdose or poisoning in hospitalized patients or to assist in a medicolegal death investigation. Plasma levels