Metoprolol succinate side effects
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Common and Rare Side Effects of Metoprolol Succinate
Mild Side Effects: Fatigue, Bradycardia, and Tolerability
Metoprolol succinate is generally well tolerated in patients with mild to moderate hypertension. The most commonly reported mild side effects include fatigue and mild sinus bradycardia (slow heart rate), which were observed in a small number of patients during clinical use. Most patients do not experience significant adverse effects at standard therapeutic doses, and the medication is considered effective and safe for blood pressure control in these cases .
Rare and Serious Side Effects: Skin Reactions, Hypertriglyceridemia, and Hyperkalemia
Although rare, metoprolol succinate can cause more serious side effects. There has been a reported case of erythema multiforme, a skin reaction characterized by red patches and burning pain, following the use of metoprolol succinate. This reaction is unusual but important for clinicians to recognize .
Another rare side effect is marked hypertriglyceridemia, where triglyceride levels in the blood rise significantly. In one case, a patient developed triglyceride levels exceeding 1000 mg/dL, along with fatigue and mild abdominal discomfort, after starting metoprolol succinate. The triglyceride levels returned to normal after stopping the medication, highlighting the need for monitoring lipid levels in patients who develop new-onset hypertriglyceridemia while on this drug .
Hyperkalemia, or elevated potassium levels in the blood, is also a very rare but potentially serious side effect. There are only a few reported cases, mostly in patients with diabetes but without kidney problems. Potassium levels normalized quickly after discontinuing metoprolol succinate, suggesting a direct link to the medication .
High-Dose and Animal Study Findings: Organ Toxicity and Cardiotoxicity
Animal studies using much higher doses than those prescribed to humans have shown that metoprolol succinate can cause mild central nervous system depression, reduced body weight, and even death at very high doses. The most affected organs in these studies were the heart, liver, kidney, and intestine, with evidence of cardiotoxicity such as increased heart weight and changes in heart shape. However, these effects were observed at doses much higher than those used in clinical practice .
Conclusion
Metoprolol succinate is generally safe and well tolerated at standard doses, with mild side effects like fatigue and bradycardia being the most common. Rare but serious side effects include skin reactions, severe increases in blood triglycerides, and hyperkalemia. High-dose animal studies suggest potential organ toxicity, but these findings are not typically relevant to standard human use. Clinicians should be aware of these rare risks and monitor patients accordingly, especially if unusual symptoms develop.
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