There are a number of possible metoprolol side effects, it is best to speak to your doctor about these and consult with him/her should any of these persist and become bothersome. The side effects listed below pertain to the orally administered form of this medication.
- NOTE: If you experience symptoms of an allergic reaction which often involve a combination of itching, the development of a rash or hives, difficulty breathing and noticeable swelling of the face, lips, throat and / or tongue visit your doctor or an emergency room immediately.
Common metoprolol side effects
Some of the more common side effects that may be experienced when taking metoprolol (sold as Lopressor, Toprol XL, Betaloc, Lopresor) include:
- Bradycardia (abnormally slow heart beat): This is defined as a resting heart rate of 60 beats per minute or less. Metoprolol slows down nerve impulses travelling from the brain to the heart, which can, in turn, slow your heart rate. A severely lowered pulse can compromise oxygen flow to the brain and body. Symptoms of this condition include:
- Fatigue
- Confusion
- Dizziness
- Shortness of breath
- Fainting
- Chest pains
- Cold hands and feet
- Cold hands and feet: The slowing of the heart rate and lowering of the blood pressure caused by this medication can result in decreased circulation and less blood being pumped to the hands and feet. This results in a loss of warmth, making them feel cold and, on occasion, painful.
- Diarrhoea: Metoprolol can block the nerve signals sent from the brain to the gut which can affect the digestive system, either speeding it up or slowing it down. If it moves faster it can result in diarrhoea, and if it moves slower it results in constipation.
- Dizziness: Due to its blood pressure lowering effects, metoprolol may cause mild dizziness, particularly when moving quickly from a lying or seated position to a standing one (this has been reported in 2 to 10% of users). This feeling will often disappear when the body has adjusted to the drug. However, severe drops in blood pressure may result in severe dizziness and fainting, which is considered a serious side effect. It is best to consult with a doctor should you experience either of these.
- Fatigue, drowsiness and weakness: Metoprolol will slow your heart rate down by blocking the hormone adrenaline. This results in blood being transported to the brain and body at a slower pace, making some feel tired (reported in 1 to 10% of cases), drowsy and weak. This symptom may fade after a few days when first taking the drug as the body adapts to its effects. If fatigue persists or worsens, speak to your doctor.
- Gastrointestinal issues: In addition to diarrhoea, metoprolol may cause other gastrointestinal issues such as constipation, abdominal pain, heartburn, bloating, gas, flatulence, nausea and vomiting.
- Headache
- Heart palpitations: With beta blocker use the atrium (the upper chamber in which blood enters the heart) does not fill or contract as hard and effectively. The atrium then becomes stretched and stiff. This causes poor conduction of the electric signal telling the heart to contract and ultimately leads to irregular heartbeats and atrial fibrillation (a condition wherein the upper and lower chambers of the heart to beat irregularly out of sync). If you experience palpitations, shortness of breath and fatigue after taking metoprolol, speak to your doctor as he/she may wish to change your medication.
- Hypotension (low blood pressure): Metoprolol is prescribed to lower blood pressure. If the dosage is too high, this may result in a severe drop in blood pressure. This can also be a result of heart receptors being overly sensitive to the drug. Symptoms of hypotension may include light-headedness, severe dizziness or fainting.
- Shortness of breath: This symptom may be experienced, particularly when engaging in physical activity, due to the fact that metoprolol hinders the effect of adrenaline (epinephrine) and noradrenaline (norepinephrine) on the lungs. These hormones relax the small airways (bronchioles) of the lungs, making breathing easier, when they are inhibited, shortness of breath may occur. Metoprolol also affects cardiac output (reducing the volume of blood that is pumped by the heart) which can decrease the amount of oxygen in the body, leaving you short of breath. If you have a predisposition to respiratory issues or experience this side effect, discuss this with your doctor during your initial consultation or as soon as possible after being prescribed and taking this medication. Beta blockers such as Metoprolol are rarely prescribed to patients with asthma as this medication can exacerbate this condition.
Other side effects of metoprolol
In addition to the above, other side effects may include:
- Chest pain / discomfort: Metoprolol, despite being used to treat chest pain (angina), may actually cause or worsen it in some people. This is due to the fact that it slows the heart rate, which in severe cases can lead to pain. Never ignore chest pain, always get checked out by your doctor to be safe.
- Depression: While depression is often listed as a metoprolol side effect as it has been reported by between 2 and 5% of users in clinical studies1, comprehensive studies2,3 which have examined this specific side effect have not conclusively proven or disproven metoprolol's link to drug-induced depression as yet. It is believed that those suffering from the chronic health problems for which metoprolol is often prescribed may be more susceptible to suffering depression as well. If you do find yourself feeling depressed after using this medication, always consult your doctor.
- Difficulty breathing and coughing: As mentioned above, metoprolol can cause shortness of breath due to the fact that it blocks the action of adrenaline on the lungs and affects the heart’s ability to pump oxygen through the blood, making it more difficult to breathe. In some instances, this inhibitory action may lead to asthma-like symptoms such as trouble breathing. Coughing and wheezing may occur. If you experience these side effects, consult your doctor.
- Fluid retention: This may lead to swelling of the face, limbs, hands and feet.
- Heart conduction disturbances: This may result from a lowered heart rate due to metoprolol use, causing what is known as a first degree atrioventricular block. In this condition, electrical impulses in the heart are slowed, generally symptoms or issues are rare.
- Increase in perspiration / sweating (diaphoresis): Metoprolol can cause heat sensitivity and excessive perspiration in some.
- Musculoskeletal pain and arthralgia (joint pain)
- Skin Issues: Metoprolol may induce the following skin related issues as side effects:
- Pruritis: Metoprolol can cause a severe itching of the skin that may be accompanied by a burning sensation.
- Rash: Skin rashes can start to develop as a result of metoprolol use. Hives and itching can also be experienced, this is considered seriousand it is important to seek professional advice from your doctor should you experience this symptom.
- Tingling in the skin / Pins and needles
- Sleep disturbances: Metoprolol may cause issues with sleep in some, these include:
- Issues with falling and staying asleep (insomnia)
- Nightmares
- Weight gain: Metoprolol (Lopressor, Toprol XL) may cause slight weight gain as a side effect. Generally, a gain of 1.2kg (2.6lb) is average. If you are taking Metoprolol to prevent heart failure and suddenly gain more than this in a day and more than 2.3kg (5.1lb) in a week, make an appointment to see your doctor immediately as this may indicate a build-up of fluid in your body, rather than actual weight gain which may be a result of your condition worsening.
- Worsening of heart failure symptoms: This may occur initially but is usually only temporary and generally resolves. You should work closely with your doctor if your symptoms worsen after taking metoprolol.
Rare metoprolol side effects
Rare metoprolol side effects affect 1 in 1000 people. They are considered to be4,5:
- Anxiety and nervousness
- Changes in liver test results
- Dry mouth (Xerostomia)
- Hair loss (alopecia): Hair loss may occur, this is, however, reversible once the medication is stopped.
- Irregular heart beat (arrhythmia)
- Runny nose
- Sexual dysfunction: In men metoprolol can disrupt the section of the brain that signals an erection during sexual arousal, causing impotence. The same mechanism can also make orgasm difficult for both sexes when taking this medication.
- Peyronie's syndrome (a condition which causes the penis to bend on erection) may also occur in rare instances.
- Visual disturbances: Visual side effects reported when taking Metoprolol include:
- Blurred vision which may cause difficulty in focussing on objects both near and far. This is due to the fact that beta blockers like metoprolol can lower intraocular pressure (IOP) by decreasing fluid production in the eye6. When IOP is very low, this may lead to blurred vision.
- Double vision
- Dry eyes7 (as a result of metoprolol reducing fluid production in the eye)
- Conjunctivitis
- Unstable diabetes
Very rare side effects of metoprolol
Affecting 1 in 10,000 people, very rare metoprolol (lopressor / Toprol XL) side effects include:
- Arthritis
- Changes in blood cells
- Changes in blood triglycerides and a decrease in High Density Lipoprotein (i.e. the 'good' type of cholesterol).
- Changes in taste: Things that once tasted good may not taste the same, this can affect appetite.
- Cognitive issues:
- Confusion
- Forgetfulness
- Hallucinations
- Temporary memory loss (amnesia)
- Changes in personality (mood)
- Hearing issues:
- Difficulty hearing
- Ringing in the ears (tinnitus)
- Light sensitivity (photosensitivity)
- Liver inflammation (hepatitis)
- Jaundice (yellowing of the skin, mucous membranes and whites of the eyes due to high levels of bilirubin in the body)
- Psoriasis (new cases or exacerbation of existing ones)
- Tissue death (necrosis) in those suffering from severe circulation disorders.
References
1. Harvard Health Publishing. Harvard Medical School. October 2015. Is your medication making you depressed? Available: https://www.health.harvard.edu/drugs-and-medications/is-your-medication-making-you-depressed [Accessed 18.07.2018]
2. US National Library of Medicine. December 2008. General Medical Drugs Associated with Depression. Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2729620/ [Accessed 18.07.2018]
3. US National Library of Medicine. January 2017. Impact of metoprolol treatment on mental status of chronic heart failure patients with neuropsychiatric disorders. Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5279819/ [Accessed 18.07.2018]
4. The electronic Medicines Compendium (eMC). Metoprolol tartrate film-coated tablets. Available: https://www.medicines.org.uk/emc/files/pil.5200.pdf [Accessed 18.07.2018]
5. US Food and Drug Administration. LOPRESSOR (metoprolol tartrate) tablet. Available: https://www.accessdata.fda.gov/drugsatfda_docs/label/2008/017963s062,018704s021lbl.pdf [Accessed 18.07.2018]
6. The Optometric Extension Program Foundation. Ocular & visual side effects of systemic drugs. Available: https://www.oepf.org/sites/default/files/journals/jbo-volume-11-issue-6/11-6%20Valeriewren.pdf [Accessed 18.07.2018]
7. Research Gate. August 2012. The Role of Medications in Causing Dry Eye. Available: https://www.researchgate.net/publication/232227209_The_Role_of_Medications_in_Causing_Dry_Eye [Accessed 18.07.2018]