Metoprolol is a drug that belongs to the group of the selective β1 receptor blockers. It acts due to influence on heart and blood flow.
Metoprolol can be used for the treatment of such conditions as hypertension, coronary artery disease, angina pectoris, acute myocardial infarction (treatment and secondary prophylaxis), cardialgia, vasovagal syncope, supraventricular tachycardia, ventricular tachycardia, long QT syndrome, congestive heart failure, hypertrophic cardiomyopathy, thyrotoxicosis (as a part of complex therapy) and prevention of migraine headaches.
Side effects
According to study’s data about 27% of patients who use Metoprolol experience at least one side effect. Some of them mild and transient but can be quite serious and require urgent medical attention. Metoprolol can be metabolized in two ways and patients who are slow metabolizers can experience more often and severe side effects.
The most common side effects of Metoprolol are:
- Headache
- Tiredness
- Dizziness
- Tinnitus (ringing in one or both ears)
- Drowsiness
- Anxiety
- Confusion
- Lightheadedness
- Foggy thinking
- Fainting spells
- Ataxia
- Short-term memory loss
- Cold, tingling, or numbness in fingers and toes
- Arthralgias
- Muscle pain
- Cramps
- Mild flu symptoms (chills, fever, runny nose, cough and sore throat)
- Increased asthma attacks in patients with pre-existing asthma
- Shortness of breath
- Wheezing
- Low blood pressure
- Chest pain
- Slow heart rate
- Arrhythmia
- Difficulty in swallowing
- Increased thirst
- Dry mouth
- Nausea
- Vomiting
- Heartburn
- Stomach pain
- Constipation
- Gas
- Diarrhea
- Decreased urination
- Reversible hair loss (alopecia)
- Dry mouth or eyes
- Conjunctivitis
- Eye pain
- Decreased vision clearness
- Yellowing of the skin or eyes
- Swelling and redness at injection site
- Itching
- Urticaria
- Unexplained rash
- Somnolence
- Insomnia
- Nightmares
- Depression
- Sexual dysfunction
- Erectile dysfunction
- Peyronie’s disease
Other less common side effects that can develop in people who use Metoprolol include:
- Hepatitis
- Worsening of psoriasis
- Photosensitivity
- Arthritis
- Claudication
- Anorexia
- Diabetes mellitus
- Red, swollen, blistered, or peeling skin
- Generalized psoriasiform lesions
- Arterial insufficiency of the Raynaud type
- Palpitations
- Emotional lability
- Slightly clouded sensorium
- Paresthesias
- Retroperitoneal fibrosis
Also side effects of the Metoprolol can be invoked by its sudden withdrawal. It can cause such adverse reactions as sweating, chest pain, breathing trouble and arrhythmia (irregular or fast heartbeat). In patients with angina pectoris stopping of Metoprolol intake can cause quite serious aggravation of the angina symptoms.
As any other medicine Metoprolol can cause allergic reaction that can manifest in:
- Severe dizziness
- Unexplained rash
- Hives
- Itching
- Unexplained swelling of the face, eyes, mouth, lips, tongue, neck
- Wheezing
- Unusual hoarseness
- Difficulty in breathing or swallowing
- Tightness in the chest
Serious side effects
Patients who use Metoprolol can experience serious adverse effects that may require emergent medical help. Such side effects include:
- Unexplained swelling the arms, legs, hands, or feet (peripheral edema)
- Sudden weight gain
- Hypotension
- Arrhythmia (severe bradycardia or irregular heartbeat)
- Heart block of the first-, second- or third-degree
- Intensification of AV block
- Variant angina pectoris (coronary artery spasm)
- Congestive heart failure
- Cardiogenic shock (especially when used post myocardial infarction)
- Increased bronchospasm
- Severe respiratory distress
- Severe dizziness or lightheadedness
- Hepatitis
- Bowel or urethral obstruction
- Hypoglycemia
- Hyponatriemia (confusion, seizures, sluggishness)
- Hyperkalemia
- Unusual bruising or bleeding
- Hallucinations
- Disorientation for time and place
- Mental depression up to catatonia
- Polymyalgia rheumatica
- Gangrene
In patients with obstructive lung diseases such as asthma, chronic bronchitis, or emphysema Metoprolol can cause aggravation of breathing difficulties.
Laboratory test’s changes
Metoprolol also can cause some changes in your blood tests. So if your doctor reveals in your blood tests such biochemical abnormalities as increased liver enzymes (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and lactic dehydrogenase), dyslipidemia (elevated serum triglyceride, very low density lipoproteins (VLDL) and significantly decreased high density lipoproteins (HDL)) you should keep on your mind that these can be result of the Metoprolol’s adverse effects.
Also if you use Metoprolol it can lead to low blood sugar level (hypoglycemia), increased level of the serum potassium (hyperkalemia), low blood sodium levels.
Hematological picture during Metoprolol’s intake can be changed in such way as agranulocytosis, microcytic anemia, nonthrombocytopenic purpura, thrombocytopenic purpura.
Hormonal test can show decreased free and total testosterone and slightly decreased T3 concentrations in serum.
Side effects in pregnant women
There were not held proper studies to establish safety of the Metoprolol’s use pregnancy. But there are data that Metoprolol can slow fetus development.
Nursing mothers should use this medicine under doctor’s supervision because Metoprolol can pass into the milk and cause side effects in the infant.
Side effects in children
There were not held proper studies to establish safety of the Metoprolol’s in children.
Conclusions
You may never experience any of listed above side effects. And your doctor cannot predict reaction of your body to Metoprolol until you will try it. That’s why don’t forget to let your physician know if something in your health condition alert you. So when it seems that anything going wrong ask your doctor for advice and he or she will diagnose if your problem is connected with medicine intake. And be careful because some of Metoprolol’s side effects require urgent medical help. Also do not stop intake of Metoprolol suddenly because it can cause side effects and worsening of your symptoms.