Metoprolol: A Detailed Guide to 10 Side Effects and When to Contact Your Doctor
Metoprolol is a medication in the beta-blocker class. It is commonly prescribed for conditions such as high blood pressure (hypertension), chest pain (angina), irregular heart rhythms (arrhythmias), heart failure, and after a heart attack. It works mainly by blocking the effects of adrenaline on the heart, which slows the heart rate, reduces blood pressure, and decreases the heart’s workload.
Common brand names include Lopressor (metoprolol tartrate) and Toprol-XL (metoprolol succinate).
Important: Do not stop metoprolol suddenly unless your healthcare professional tells you to. Sudden withdrawal can worsen chest pain or increase the risk of serious heart problems, especially in people with heart disease.
10 Common and Important Side Effects of Metoprolol
1. Slow Heart Rate (Bradycardia)
What happens:
Metoprolol intentionally slows the heartbeat to reduce the heart’s workload. In some people, the heart rate can become slower than desired.
Possible symptoms:
- Feeling unusually tired or weak
- Dizziness or lightheadedness
- Fainting or near-fainting
- Shortness of breath during activity
- Feeling like your heart is beating very slowly
When to call your doctor:
Contact your healthcare provider if:
- Your resting pulse is repeatedly very low (for example, below about 50 beats per minute unless your doctor has told you this is expected)
- You feel faint, confused, or unusually weak
Seek urgent care if you faint, have severe dizziness, or develop chest pain.
2. Low Blood Pressure (Hypotension)
What happens:
Because metoprolol lowers blood pressure, some people experience blood pressure that drops too much.
Symptoms:
- Dizziness when standing up
- Blurred vision
- Weakness
- Feeling like you may pass out
- Cold hands and feet
Helpful tips:
- Stand up slowly from sitting or lying positions.
- Stay hydrated unless you have been instructed to restrict fluids.
- Monitor blood pressure if your doctor recommends it.
Call your doctor if:
Low blood pressure symptoms are frequent or interfere with daily activities.
3. Fatigue and Tiredness
What happens:
Metoprolol reduces adrenaline activity, which can make some people feel less energetic, especially when starting treatment.
Symptoms:
- Low energy
- Sleepiness
- Reduced exercise tolerance
- Feeling sluggish
What to know:
This often improves after the body adjusts over several weeks.
Talk to your doctor if:
- Fatigue is severe
- You cannot perform normal activities
- Symptoms continue for a long time
Your doctor may adjust the dose or consider alternatives.
4. Dizziness
Why it happens:
Dizziness may result from:
- Lower blood pressure
- Slower heart rate
- The body adjusting to the medication
Symptoms:
- Lightheadedness
- Feeling unsteady
- Trouble concentrating
Reduce risk:
- Rise slowly after sitting or lying down.
- Avoid driving or operating machinery until you know how the medication affects you.
Get medical advice if:
Dizziness is severe, persistent, or associated with fainting.
5. Cold Hands and Feet
Why it happens:
Beta-blockers can reduce blood flow to the hands and feet by affecting circulation.
Symptoms:
- Cold fingers or toes
- Tingling sensations
- Numbness
Usually:
This side effect is uncomfortable but not dangerous.
Contact your doctor if:
- Fingers or toes become painful, pale, blue, or severely numb
- Symptoms are worsening
6. Sleep Problems and Vivid Dreams
Possible effects:
Some people experience:
- Trouble falling asleep
- Frequent waking
- Unusual or vivid dreams
- Nightmares
Why:
Beta-blockers may affect nervous system activity and sleep patterns.
What may help:
- Taking the medication at a different time (only if approved by your doctor)
- Maintaining a consistent sleep schedule
- Avoiding caffeine late in the day
Tell your doctor if:
Sleep problems are severe or affecting your quality of life.
7. Depression or Mood Changes
Possible symptoms:
- Low mood
- Loss of interest in activities
- Feeling emotionally “flat”
- Increased sadness or irritability
Important:
Mood changes are not among the most common effects, but they can occur.
Contact your doctor if:
- You notice significant mood changes
- Depression symptoms persist
- You have thoughts of self-harm (seek immediate emergency help)
8. Shortness of Breath or Breathing Problems
Why it matters:
Metoprolol can sometimes worsen breathing problems in sensitive individuals, especially those with asthma or certain lung diseases.
Possible symptoms:
- Wheezing
- Chest tightness
- Difficulty breathing
- Reduced ability to exercise
Seek medical advice promptly if:
Breathing becomes noticeably worse.
Emergency help is needed for:
- Severe breathing difficulty
- Blue lips or face
- Severe chest tightness
9. Blood Sugar Changes (Especially in Diabetes)
What happens:
Metoprolol can sometimes hide warning signs of low blood sugar, particularly the fast heartbeat usually felt during hypoglycemia.
Symptoms of low blood sugar may include:
- Sweating
- Shaking
- Confusion
- Hunger
- Irritability
- Weakness
Important for people with diabetes:
Continue monitoring blood glucose as recommended.
Call your doctor if:
Your blood sugar control changes or you have repeated low blood sugar episodes.
10. Sexual Side Effects
Possible effects:
Some people report:
- Reduced sexual desire
- Difficulty achieving or maintaining an erection
- Changes in sexual performance
What to do:
Do not stop the medication on your own. Other causes may also contribute, including blood pressure, diabetes, stress, or other medications.
Discuss concerns with your healthcare provider.
Serious Side Effects: Get Medical Attention Quickly
Contact a doctor urgently or seek emergency care if you experience:
Heart-related warning signs:
- Chest pain that is new, severe, or worsening
- Fainting
- Severe slow heartbeat
- New swelling of legs, ankles, or feet
- Sudden weight gain with breathing difficulty
Severe allergic reaction:
- Swelling of face, lips, tongue, or throat
- Trouble breathing
- Severe rash
Possible worsening heart failure:
- Increasing shortness of breath
- Difficulty lying flat due to breathing problems
- Rapid fluid buildup or swelling
Who Should Be Extra Careful With Metoprolol?
Tell your doctor if you have:
- Asthma or chronic lung disease
- Very slow heart rate
- Heart block or certain electrical heart problems
- Severe circulation problems
- Diabetes
- Thyroid disease
- Liver disease
- History of severe allergic reactions
Drug and Food Considerations
Metoprolol may interact with:
- Other blood pressure medicines
- Certain heart rhythm medications
- Some antidepressants
- Alcohol (may increase dizziness or low blood pressure)
- Some medications that affect liver enzymes
Always provide your healthcare provider with a complete list of medications and supplements.
Do Not Stop Metoprolol Suddenly
Stopping suddenly may cause:
- Increased heart rate
- Increased blood pressure
- Worsening chest pain
- Increased risk of heart attack in some patients
Doctors usually reduce the dose gradually when stopping treatment.
Quick Summary: When to Call Your Doctor
| Symptom | Action |
|---|---|
| Mild tiredness when starting | Monitor and discuss if persistent |
| Dizziness or low blood pressure | Contact doctor if frequent |
| Very slow pulse with symptoms | Seek medical advice promptly |
| Fainting | Urgent medical attention |
| Chest pain | Emergency evaluation |
| Severe breathing problems | Emergency care |
| New swelling or sudden weight gain | Contact doctor |
| Severe mood changes | Discuss promptly |
Metoprolol is considered an effective and generally well-tolerated medication when used correctly. Many side effects improve as the body adjusts, but symptoms involving fainting, chest pain, severe breathing difficulty, or major heart-rate changes deserve prompt medical attention.