What Are the Side Effects of Metoprolol Tartrate?

Metoprolol tartrate (Lopressor) is a medicine most commonly used to treat high blood pressure. It belongs to a group of medicines called beta-blockers. Metoprolol works by relaxing blood vessels and slowing the heart rate. In addition to hypertension, it may be used to treat and prevent heart-related chest pain and to alleviate strain on the heart due to a heart attack. As with all medications, metoprolol may cause side effects that range from mild to severe.

Woman with headache (Image: Jose Luis Pelaez Inc… /Blend Images/Getty Images)

Dizziness When Standing

Lightheadedness, dizziness or fainting when getting out of bed or standing up quickly is a possible side effect of metoprolol. These symptoms occur because of a sudden decrease in your blood pressure. To help your body get used to the change in position, get up slowly, especially from the bed or a chair. Discuss this side effect with your health care provider if you notice these symptoms. Your doctor may need to change your dosage.

Blood Sugar Changes

Metoprolol may affect your blood sugar levels if you have diabetes. You may need to check your blood sugar more often when starting this medication. Metoprolol may also hide some of the symptoms of hypoglycemia, or low blood sugar. The drug may also increase the amount of time it takes to recover from low blood sugar. Discuss your diabetes care with your doctor because your diabetes medicines may need to be adjusted while you are on metoprolol.

General Side Effects

Approximately 10 percent of people who take metoprolol report tiredness and lack of energy. Less common side effects include headaches, nausea, poor concentration, depression and sleeping problems. These side effects are usually mild, but talk with your health care provider if they become bothersome. Metoprolol and other beta-blockers can also cause erectile dysfunction. Talk with your doctor if you experience this side effect.

Rare But Serious Side Effects

Some rare but serious side effects include difficulty breathing or a severe allergic reaction. Seek immediate medical care if you experience swelling of the face, lips, tongue or throat, or chest tightness, difficulty breathing or wheezing. Contact your doctor right away if you experience shortness of breath, swelling of your legs or feet, changes in your heart rate or heart fluttering.