Metoprolol is a commonly prescribed beta blocker used to treat several cardiovascular conditions, including high blood pressure, angina, certain abnormal heart rhythms, heart failure, and problems that may occur after a heart attack.
For many people, metoprolol is effective and well tolerated. Like every medication, however, it can cause side effects. Some are relatively common and may improve as the body adjusts, while others are less common but deserve prompt medical attention.
The risk of side effects depends on the dose, the reason metoprolol is being used, age, kidney and liver function, other health conditions, and interactions with other medicines.
One of the most important safety points is this: do not suddenly stop metoprolol without medical advice. Abrupt withdrawal can cause the heart rate and blood pressure to rise and may worsen angina or other cardiovascular problems in susceptible people.
Here are 10 important effects to recognize, along with the symptoms that should prompt a conversation with your doctor or pharmacist.
What Is Metoprolol?
Metoprolol belongs to a class of medicines called beta blockers.
It primarily blocks beta-1 adrenergic receptors in the heart. This reduces the effects of adrenaline and related stress hormones on the cardiovascular system.
As a result, metoprolol can:
Slow the heart rate
Reduce the force of heart contractions
Lower blood pressure
Reduce the heart’s oxygen demand
Help control certain abnormal heart rhythms
These effects explain both why the medicine is useful and why some of its side effects occur.
Metoprolol Tartrate and Metoprolol Succinate
Metoprolol is available in different formulations.
Metoprolol tartrate is generally an immediate-release form, while metoprolol succinate is an extended-release formulation.
They are not always prescribed in exactly the same way, and patients should not switch formulations or change dosing schedules without professional guidance.
1. Tiredness and Low Energy
Fatigue is one of the more commonly reported effects of beta blockers.
Because metoprolol slows the heart and reduces its workload, some people notice a temporary reduction in energy, particularly when starting treatment or after a dose increase.
Symptoms can include:
Unusual tiredness
Reduced exercise tolerance
During physical activity, the body normally increases heart rate in response to increased demand.
A beta blocker limits this response.
Someone who previously relied on heart rate to judge exercise intensity may therefore notice that exercise feels different after starting metoprolol.
This does not necessarily mean exercise has become unsafe, but people with cardiovascular disease should follow individualized activity recommendations.
2. Dizziness or Lightheadedness
Metoprolol can lower blood pressure and slow the heart rate. Either effect can occasionally cause dizziness or lightheadedness.
This may be especially noticeable when:
Standing up quickly
Getting out of bed
Starting treatment
Increasing the dose
Exercising
Becoming dehydrated
Taking other blood-pressure-lowering medicines
Standing up gradually can sometimes reduce symptoms related to a sudden drop in blood pressure.
If dizziness is severe, frequent, or accompanied by fainting, chest pain, confusion, or difficulty breathing, medical evaluation is important.
Driving and Dizziness
Until you know how metoprolol affects you, be cautious with driving, operating machinery, or other activities in which dizziness or unusual fatigue could create a safety risk.
3. Slow Heart Rate
A slower heart rate is an expected pharmacological effect of metoprolol.
That is often one of the reasons the medication is prescribed.
However, in some people the heart rate can become slower than intended.
Possible symptoms associated with excessive slowing include:
Weakness
Dizziness
Fainting
Unusual fatigue
Shortness of breath
Reduced exercise tolerance
Confusion in some individuals
The meaning of a specific pulse rate depends on the individual. Athletes, for example, may naturally have relatively slow resting heart rates.
Do not change or skip your dose based only on one pulse reading unless a healthcare professional has specifically instructed you to do so.
When a Slow Heart Rate Needs Attention
A very slow pulse accompanied by fainting, severe weakness, difficulty breathing, chest discomfort, or confusion should be evaluated promptly.
Your clinician may review your dose and other medications that can also slow the heart.
Medicines That May Add to the Heart-Rate-Lowering Effect
Other drugs that affect heart rate or electrical conduction can sometimes amplify metoprolol’s effects.
This is why your doctor and pharmacist should know about every prescription medication, over-the-counter product, and supplement you take.
A slower pulse can be an intended effect of metoprolol, but slow heart rate plus fainting, severe weakness, or breathing difficulty is a different situation and should not simply be ignored.
4. Low Blood Pressure
Metoprolol is often prescribed specifically because it lowers blood pressure.
