RECALL OF METFORMIN EXTENDED RELEASEIn 2020 and 2021, the
Food and Drug Administration (FDA) and some manufacturers recalled some extended release metformin tablets from the U.S. market. This is because an unacceptable level of a probable carcinogen (cancer-causing agent) was found in some extended-release metformin tablets. If you currently take this drug, call your healthcare professional. They will advise whether you should continue to take your medication or if you need a new prescription.
Key takeaways
- Consuming grapefruit while taking metformin is generally considered safe, as there are no known interactions between the two. While grapefruit contains compounds that can affect the way some other medications work, the body does not metabolize metformin in the same way as these other drugs.
- As other medications can interfere with metformin’s effectiveness or increase the risk of harmful effects, it is important to discuss all medications with a doctor.
- Some studies suggest that grapefruit may have benefits for people with diabetes, potentially helping to lower blood sugar levels, but more research is necessary.
Doctors often prescribe metformin as a first-line treatment for people with type 2 diabetes. Metformin works by helping to lower a person’s blood sugar levels. Doctors sometimes also recommend metformin treatment for people with polycystic ovary syndrome (PCOS).
Grapefruit and grapefruit juice are good sources of potassium and vitamin C, which are both essential nutrients. However, the United States
This article explains whether grapefruit interacts with metformin, plus what to avoid while taking metformin. It also covers whether grapefruit is good for diabetes and why grapefruit interacts with some drugs.
Grapefruit is unlikely to interact with metformin.
Currently, experts know of more than 85 drugs that may interact with grapefruit.
The FDA requires that certain medications, including some over-the-counter (OTC) drugs, carry warnings about consuming grapefruit while taking these medications.
However, metformin does not carry this warning, and there is no scientific evidence to suggest that grapefruit affects the safety or effectiveness of taking this medication.
Certain medications can potentially interact with metformin and may either reduce its effectiveness or increase the risk of harmful effects.
These medicines include:
- oral contraceptives
- diuretics
- corticosteroids
- phenytoin (Dilantin, phenytek, Epanutin)
- nicotinic acid or niacin (Niaspan, Niacor, Endur-acin)
- calcium channel blockers
- glyburide (Diabeta, Micronase, Daonil)
- epilepsy medications
- thyroid products
- isoniazid (Nydrazid, Hydra, Rifinah)
- nifedipine (Adalat, Procardia, Nifedipress)
- furosemide (Lasix, Frusol)
- sympathomimetics, often used to treat ADHD, shock, asthma, and nasal congestion
- phenothiazines, often used as antipsychotics, anti-vomiting, or antihistamine medications
Alcohol use when taking metformin can also increase the risk of low blood sugar levels. People on metformin should avoid drinking alcohol or drink
Before taking metformin, it is essential for a person to inform doctors and pharmacists of any medications they use. Also, do not stop taking any prescribed medications in order to take metformin without checking with a doctor first.
Although grapefruit contains natural sugar, unsweetened grapefruit juice and whole raw grapefruit have a low glycemic index and low glycemic load, meaning they are unlikely to cause sharp or sudden blood sugar spikes.
Also, in addition to containing key nutrients, some evidence suggests that grapefruit may even help lower blood sugar levels. However, researchers are not yet sure why.
In a
The researchers stated that the mice drank the equivalent of an adult weighing 70 kilograms drinking 3.5 to 4 cups of grapefruit juice a day. Further research is needed to determine whether this is safe and similarly beneficial in humans.
In a 2015 study, rats with drug-induced diabetes that drank grapefruit juice for 60 days experienced a decrease in fasting blood sugar levels compared to those that just drank water.
The researchers believe that this result was due to compounds in the grapefruit juice reducing glucose production in the rats’ livers.
While these studies suggest potential benefits of grapefruit for diabetes, more recent, high quality research is needed to confirm these effects in humans.
Researchers have identified two ways that consuming grapefruit may interact with certain drugs.
Drug metabolism
Compounds in grapefruit called furanocoumarins can block the function of CYP3A4, a digestive enzyme that helps the body metabolize approximately 50% of drugs.
Blocking this enzyme means that certain drugs stay in the body for longer than normal and build up in the bloodstream, increasing the risk of harmful effects. In some cases, this can be fatal.
Drug absorption
Grapefruit juice also contains plant compounds called flavonoids, including naringin and hesperidin.
Research reports that some of these flavonoids can block a protein called organic anion transporter polypeptide (OATP). The OATP protein allows drugs to move into cells.
This means that consuming grapefruit can decrease the body’s absorption of certain drugs, making them less effective. It is recommended to consult a doctor or pharmacist before consuming grapefruit while taking any medications.
Why metformin is different
The body does not metabolize metformin at all, and there is no interaction with CYP3A4. Instead, metformin passes through the body unchanged and leaves through a person’s urine.
This lack of metabolism is the reason why grapefruit does not interact with metformin.
Although grapefruit is nutritious, the compounds it contains can affect the safety or effectiveness of a wide range of medications. The FDA requires these medications to include a warning about the potential interactions with grapefruit for people who take these drugs.
Metformin does not carry this warning, and there is no evidence to suggest that grapefruit interacts with metformin. This is because the body does not metabolize metformin, and so it is not affected by grapefruit’s ability to block the function of digestive enzymes and proteins, which would otherwise lead to interactions.
When taking any medication, it is essential to read the packaging fully and follow the instructions provided by doctors and pharmacists.