Does St John’s Wort interact with metoprolol? (5+ tips)

This article discusses whether Saint John’s Wort interacts with metoprolol. It will discuss relevant research studies and explain the mechanisms by which they may interact together. Additionally, the article mentions the side effects of Saint John’s Wort and metoprolol.

Finally, the article will provide suggestions on how to take St. John’s Wort and metoprolol together to maximize safety and effectiveness.

Does St John’s Wort interact with metoprolol?

Saint John’s Wort (SJW) may interact with metoprolol in some people. However, while SJW interacts with various drugs, its interaction with metoprolol is not a popular or commonly reported one.

Saint John’s Wort is a medicinal herb with a lot of benefits and uses. It unselectively inhibits the reuptake of certain neurotransmitters, including serotonin. It is mainly used for its antidepressive and anxiolytic effects. It also has antiviral effects and can be used with antibiotics for certain bacterial infections [1].

On the other hand, metoprolol is a beta 1 receptor blocker, and it is mainly prescribed for treating cardiovascular conditions, including high blood pressure, angina, and heart failure. SJW and metoprolol have different uses and mechanisms, and it is not common for them to interact.

However, people react to medications differently, and people with high sensitivity to medications or those with kidney or liver diseases may experience interactions between SJW and metoprolol. If you are worried that Saint John’s Wort may affect propranolol, you can discuss this with your doctor.

What does research suggest?

There isn’t any research that specifically investigates the interactions between SJW and metoprolol, nor is there any study that found a potential interaction between the two. However, there is a study that suggests an interaction between St. John’s Wort and another beta-1 blocker, talinolol [2].

For instance, taking Saint John’s Wort for twelve days only resulted in a 31% reduction in the availability of talinolol in the body. It also increased the oral clearance of tinolol by 93%. The study concluded that this was due to St. John’s Wort’s induction of intestinal P-glycoprotein [2].

Furthermore, research states that Saint John’s Wort mainly interacts with drugs that are metabolized via CYP3A4 enzymes. To illustrate, SJW increases the activity of these enzymes, leading to a faster breakdown of these drugs and reducing their potency [3].

However, metoprolol is mainly metabolized by CYP2D6 enzymes and only slightly metabolized by CYP3A4 enzymes. This may be the reason why the interaction between SJW and metoprolol isn’t common [4].

What are the side effects of combining SJW and metoprolol?

Saint John’s Wort and metoprolol can be safely taken together by some people without worrying about the risk of interaction. However, it is important to consider that a few people may experience increased side effects if they take the two together.

The table below illustrates the potential side effects of SJW and propranolol [1,5]:

Considerations before taking St. John’s Wort and metoprolol

If you’re thinking about taking St. John’s Wort and metoprolol together, the following factors should be considered:

• You should talk to a doctor before taking metoprolol with Saint John’s Wort; they will assess your medical and medication history to determine whether this combination is safe for you.

• If you are already administering an antidepressant, such as Celexa or sertraline, you must not take St. John’s Wort, as this can result in serotonin syndrome. 

• You should begin with low doses of Saint John’s Wort, especially if you’re taking it for the first time or combining it with a prescription drug for the first time. If you feel like you need to increase the dose, you should only increase it gradually under the supervision of a doctor.

• Don’t take St. John’s Wort if you’re already taking digoxin, oral contraceptives, theophylline, warfarin, immunosuppressants, or benzodiazepines. This herb increases the breakdown of these drugs and reduces their potency. Thus, in this case, you can only take metoprolol.

• You may need to increase the dose of metoprolol if you are taking Saint John’s Wort with it, as SJW can increase its clearance and reduce its potency. However, increasing metoprolol’s dose can cause serious side effects, so this must only be done under a doctor’s supervision.

• Saint John’s Wort can cause sedation as a side effect, while metoprolol causes dizziness and orthostatic hypotension. Thus, combining them increases the risk of falls, especially in the elderly. It is important for older people who are taking them together to avoid standing up suddenly.

Understanding the impacts of taking SJW and metoprolol

Based on my research, I concluded that Saint John’s Wort and metoprolol can interact, but that’s not very common. I found that, in a trial, Saint John’s Wort decreased the bioavailability of another beta 1 adrenergic blocker.

Based on my knowledge, Saint John’s Wort increases CYP3A4 enzymes, which leads to increased metabolism and decreased effectiveness of certain medications. I believe that this mechanism is not very serious when combined with metoprolol because metoprolol is mainly metabolized by other enzymes.

While there are no reported interactions between SJW and metoprolol, I recommend consulting with a doctor before combining them, especially if you are taking antidepressants, oral contraceptives, digoxin, theophylline, or warfarin.

Additionally, I believe that elderly people should be extra careful while combining SJW and metoprolol, as the sedation and dizziness side effects can lead to falls.

References