Published June 18 2018
Beta blockers are commonly prescribed to those with hyperthyroidism and Graves’ disease. While antithyroid medication (i.e. Methimazole, PTU) helps to lower thyroid hormone levels, beta blockers mainly help with the cardiovascular symptoms associated with hyperthyroidism, although some beta blockers can inhibit the conversion of T4 to T3. In this article I’ll discuss how beta blockers work, the different types of beta blockers, as well as some of the more common side effects of beta blockers. I’ll also discuss some natural alternatives to consider.
Beta blockers work by binding to beta-adrenoceptors, which are also known as beta-adrenergic receptors. This is how they get the name “beta” blockers. The beta-adrenoceptors play an important role in the regulation of heart function. Beta-adrenergic receptors bind both epinephrine and norepinephrine, which in turn play a role in myocardial metabolism, heart rate, and systolic and diastolic function (1) (2). While healthy levels of epinephrine and norepinephrine are important, in hyperthyroidism these levels are increased, which is what causes the elevations in heart rate, and sometimes blood pressure.
Most beta blockers reduce resting heart rate by approximately 25 to 30 beats per minute, although a lesser reduction is seen with certain beta blockers, such as oxprenolol and pindolol (3). I personally have seen reductions greater than 25 to 30 BPM, although one also needs to keep in mind that the dosage may vary depending on the severity of the cardiac symptoms. Speaking of the dosage of beta blockers someone with hyperthyroidism will need to take, this depends on a few factors, including the severity of the symptoms. With propranolol, doses can vary from 40 to 160mg/day, although doses higher than this will sometimes be given not only to decrease the resting heart rate, but to also decrease the T3 levels. Propranolol is usually taken in divided doses (i.e. 40mg every 6 hours).
In the opening paragraph I mentioned that some beta blockers will decrease the conversion of T4 to T3, which will result in lower T3 levels. The beta blockers that can do this include propranolol, atenolol, metoprolol, and alprenolol (4) (5). The way they accomplish this is by inhibiting an enzyme called 5′-monodeiodinase (6). To be more specific, certain beta blockers inhibit monodeiodinase type I (5’D-I) and monodeiodinase type II (5’D-II). This is one of the main reasons why propranolol is commonly prescribed, although as mentioned, there are a few other beta blockers that can do this as well.
Now that you have a basic understanding as to how beta blockers work, let’s take a look at some of the beta blockers that are commonly prescribed:
- Propranolol. Some people with hyperthyroidism experience “thyrotoxic hypercalcemia”, which means that they will have elevated serum calcium levels. I can’t say that I commonly see this in my practice, and the mechanism isn’t completely understood. In any case, propranolol has been shown to help people with this condition (3). This is another reason why someone with hyperthyroidism who also has elevated serum calcium levels on a comprehensive metabolic panel might be told to take propranolol.
- Atenolol. This probably is the second most common beta blocker I see patients with hyperthyroidism and Graves’ disease take. Like most other beta blockers, it can help to decrease the resting heart rate, high blood pressure, and can also help with angina (chest pain).
- Metoprolol. Although metoprolol is sometimes recommended to those with hyperthyroidism and Graves’ disease, it is more commonly recommended to treat angina (chest pain) and high blood pressure.
- Acebutolol. Acebutolol isn’t commonly recommended for hyperthyroid conditions, as it usually is used to treat high blood pressure and heart rhythm disorders.
- Timolol. In addition to helping to decrease the resting heart rate and high blood pressure, timolol can also be used as eye drops to reduce pressure inside of the eye, and is used to treat open-angle glaucoma (7).
Why Are Beta Blockers Recommended To Hyperthyroid Patients?
Not everyone with hyperthyroidism and Graves’ disease are told to take beta blockers. Here are some situations when beta blockers will be recommended:
Scenario #1: when someone has a very high resting heart rate and/or high blood pressure. Most endocrinologists will recommend antithyroid medication to help lower the thyroid hormone levels. However, if someone has a very high resting heart rate then they might also recommend for the person to take a beta blocker. Some people with hyperthyroidism also have high blood pressure, and this is another scenario when a beta blocker might be given in combination with antithyroid medication.
Scenario #2: when someone is unable to tolerate antithyroid medication. Some people are unable to take antithyroid medication, and in this situation they probably will be told to take a beta blocker to manage the cardiac symptoms. Keep in mind that while some people with hyperthyroidism take beta blockers for a few months, many endocrinologists will recommend radioactive iodine or thyroid surgery for those who are unable to tolerate antithyroid medication.
Scenario #3: when someone is planning on receiving radioactive iodine. If someone is scheduled to receive radioactive iodine, it is recommended to discontinue antithyroid medication prior to receiving this treatment, although beta blockers may be recommended to manage the symptoms.
Scenario #4: when someone has subacute thyroiditis. I’ve spoken about subacute thyroiditis in other articles, and people with this condition are likely to become hypothyroid within a few months. As a result, most medical doctors are reluctant to prescribe antithyroid medication, but if someone has an elevated resting heart rate then they may be told to take a beta blocker.
What Are The Side Effects of Beta Blockers?
Some of the common side effects of beta blockers include drowsiness, fatigue, dizziness, and weakness (8). Other less common side effects include dry mouth and eyes, dry skin, diarrhea, nausea, vomiting, and cold hands and feet (8). Some people have also reported a decreased sex drive, shortness of breath, and sleep disturbances.
It’s also important to mention that certain beta blockers can inhibit the production of CoQ10. Propranolol and metoprolol can inhibit CoQ10-dependent enzymes (9). CoQ10 has many important functions, but it is probably most well known for its role in mitochondrial health. Mitochondria are the “energy powerhouses” in our cells. As a result, anyone who is taking propranolol or metoprolol should consider taking 100mg to 200mg of CoQ10 in the form of ubiquinone, or another option is to take a lower dosage of ubiquinol.
What Natural Alternatives Are Available?
If you have been an email subscriber for awhile then you probably are familiar with some of the herbal approaches available for hyperthyroidism. I’m going to specifically focus on three herbs, and it’s important to keep in mind that while herbs can be effective in managing the cardiac symptoms (i.e. elevated resting heart rate and palpitations) in many people with hyperthyroidism, because they aren’t as potent as beta blockers, there are some cases where they aren’t suitable replacements. Speaking of which, you also need to be aware that different brands will have different potencies. Thus, if you take motherwort and it doesn’t lower your resting heart rate, there can be a few reasons for this. One reason might be because the dosage isn’t high enough, but another reason might be due to a lower potency extract.
That being said, let’s take a look at three herbs that might serve as an alternative to beta blockers in some people with hyperthyroidism:
Motherwort. This herb is also known as Leonurus cardiaca, and when I was dealing with Graves’ disease I took this herb to help with the heart palpitations I was experiencing. Think of this as a natural beta blocker, as some sources show that this herb has a blocking effect on beta adrenergic receptors. However, it is not as potent as a prescription beta blocker. In addition, motherwort has other functions, as pharmacological studies have confirmed that it has antibacterial, antioxidant, anti-inflammatory, and analgesic properties (10).
Hawthorn. This is another herb that can help to decrease the cardiac symptoms associated with hyperthyroidism. Berries, leaves, and flowers of hawthorn are phytochemically similar in composition, differing primarily in the ratio of specific flavonoids and procyanidins present (11). Apparently hawthorn doesn’t block the beta-adrenergic receptors (11) (12). Hawthorn is usually well tolerated, although some people experience vertigo and dizziness (13).
Bugleweed. I was considering not listing bugleweed here, as unlike motherwort and hawthorn, this herb has antithyroid activity. Thus, it helps to decrease cardiovascular symptoms by causing a reduction in thyroid hormone levels. The reason I thought it was important to list it here is because many people who are unable to tolerate antithyroid medication take beta blockers as the primary way of managing their symptoms. However, when working with a patient who has elevated thyroid hormone levels and is unable to take antithyroid medication, I usually will recommend for them to take bugleweed.
Warning: Don’t Abruptly Stop Taking Your Beta Blocker
Although I’ve had some patients abruptly stop taking their beta blockers, most medical doctors will recommend to gradually wean off of them. This is especially true for those people with high blood pressure, as the research shows that the abrupt cessation of beta-blockers in those people with high blood pressure increase the risk of myocardial infarction (14).
In summary, many people with hyperthyroidism and Graves’ disease take beta blockers. They are taken to help decrease the resting heart rate, although they also can help lower blood pressure. Some beta blockers also decrease the conversion of T4 to T3. Some of the common side effects of beta blockers include drowsiness, fatigue, dizziness, weakness, and certain beta blockers can also inhibit the production of CoQ10. Some natural options that can serve as an alternative to beta blockers include motherwort, hawthorn, and bugleweed.