Metformin is an FDA-approved drug recommended for the management of high blood sugar in type 2 diabetes. It helps in controlling diabetes and reduces diabetes-related complications.
Metformin can be taken in two forms, namely tablet and solution; both are taken orally. Metformin is available as a generic drug and also as a branded drug.
This article helps you understand how to use metformin, its various interactions, side effects, and warnings.
What is Metformin?
Metformin is a prescription drug; it’s available as immediate-release and extended-release. Immediate release metformin is same the as regular metformin; whereas extended-release metformin lasts longer than regular metformin and has fewer side effects, and is advised once daily with an evening dinner.
The regular metformin is available as the brand-name Glucophage, and the extended-release is available as the brand name Glucophage XR, Fortamet, and Glumetza. Both the forms are available as generic drugs, but in few cases, dosages would be different. Generic drugs cost very little compared to branded drugs. Consult your healthcare provider before choosing generic drugs (1).
Metformin helps decrease hepatic (liver) glucose production; it also reduces gastrointestinal glucose absorption and increases its insulin sensitivity.
Metformin belongs to the biguanides class of drugs, these drugs help to;
- Reduces the amount of glucose made by your liver
- Decreases the amount of glucose absorbed by your system
- Increases the effect of insulin on your body
Metformin works on the enzyme in the liver that helps to lower the glucose absorption from your diet. The best feature of metformin is that it does not cause hypoglycemia (low blood sugar) like other diabetic drugs which lead to risks such as fatigue and nausea.
Metformin helps to control high blood sugar and prevents kidney damage, blindness, nerve problems, and other risks associated with diabetes (2).
Metformin is also used to treat fertility issues in women who have PCOS. However, the FDA has not approved it for PCOS; some people use it as an off-label drug (3).
Metformin and Drug Interactions
Metformin is a prescription drug; your healthcare provider will be aware of the medicines you are already taking and suggest the dose that suits you.
Before you start taking metformin, inform your doctor if you are taking over-the-counter drugs, vitamins, herbs, or other supplements. This information can avoid potential interactions. Consult your physician or healthcare provider if you find any adverse effects when you start metformin.
Blood Pressure Drugs
People with high blood pressure are administered with diuretics; it is used to lower the blood pressure. Diuretics increase blood sugar levels. Hence taking these drugs with metformin would affect the effectiveness of metformin.
Some of the common diuretics are furosemide and hydrochlorothiazide. Nifedipine is also used to lower blood pressure, but it interacts with metformin in your body, resulting in side effects (4).
GERD Drugs
Ranitidine reduces the amount of acid in your stomach; it is advised for treating indigestion, heartburn, and acid reflux. Ranitidine is recommended for GERD. Studies suggest that when you take ranitidine and metformin, they interact, and renal clearance of metformin decreases (5).
Also, when taking metformin with cimetidine, may increase the risk of lactic acidosis. Consult your doctor before taking medicines for acidity, heartburn, or GERD, so that you will be advised with safer medications.
Glaucoma Drugs
Metformin drugs taken with glaucoma drugs such as acetazolamide, brinzolamide, dorzolamide, and methazolamide may increase your risk of lactic acidosis.
Other Diabetics Drugs
Certain diabetes drugs can interact with metformin and cause low blood sugar levels. If you are using insulin or glyburide, your physician might recommend the low dosage of other diabetes medicines so that your blood glucose level does not drop.
Hormonal Drugs
If you are taking hormonal drugs such as corticosteroids (budesonide, fluticasone, prednisone, and betamethasone) and estrogens (birth control pills, conjugated estrogens, and estradiol), consult your doctor before taking metformin; these drugs may reduce the efficacy of the metformin.
If you are taking thyroid drugs such as levothyroxine, liothyronine, and liotrix, it can make metformin less effective in reducing blood glucose.
Neural Drugs
If you are on a seizure drug such as phenytoin, metformin may be less effective due to drug interaction.
Metformin also reacts with topiramate (which is used to treat nerve pain and seizures) and increases the risk of lactic acidosis. Hence avoid taking these medicines together.
With certain antipsychotic drugs, metformin reacts and reduces the effect of lowering the blood glucose levels. Some of the antipsychotic medicines include Chlorpromazine, fluphenazine, and prochlorperazine. It is essential to consult your doctor and discuss all the drugs you have been taking (6).
What are the Side Effects of Metformin?
Metformin, an oral tablet, and suspension can cause some mild or severe side effects. Here is a list of side effects you may experience;
Short Term Side Effects
Metformin is the standard drug recommended by most doctors. Although most of the people who take it tolerate it well, according to a study, 30% of the people experience gastrointestinal problems such as vomiting, heartburn, and acidity (7).
Generally, doctors start with less dosage and increase the dosage gradually if required. Doctors suggest you take metformin with meals; this can help to prevent or reduce the GI side effects.
Mild side effects of metformin include:
- Low blood glucose
- Sometimes a runny nose
- Headache and tiredness
- Excessive sweating
- Chest discomfort
In some rare cases, when there is a drug interaction with metformin, it can cause lactic acidosis. It is a medical condition in which there is a harmful buildup of lactate in the body; this leads to reduced pH in the bloodstream. Lactic acidosis increases the risk of low blood pressure, rapid heart rate, and sometimes even death (8).
If you experience vomiting and dehydration while taking metformin, consult your doctor immediately because it may lead to lactic acidosis. Your healthcare provider may stop it temporarily until vomiting and acidity reduces, or they may suggest alternative drugs.
Lactic acidosis can also increase in some cases, such as alcohol abuse disorder, low oxygen levels, age, liver dysfunction, kidney dysfunction, and if you have undergone any surgery.
Hence, people should avoid alcohol when administered with metformin because it may increase the risk of lactic acidosis.
Long Term Side Effects
Metformin can lead to some long-term side effects if taken for an extended period of time.
It can affect the absorption of vitamin B; hence monitor your B-12 levels once in every 4-months. Vitamin B-12 deficiency can lead to several other health problems such as anemia, weak immunity; sometimes you can observe neurological symptoms and mild fatigue to severe neurological impairment.
Common symptoms of vitamin b12 deficiency include:
- Skin color change
- Nerve damage
- Fatigue
- inflammation of the tongue
- Reduced sense of smell
- Irritability and dementia-like symptoms
If you experience any of these symptoms, get your vitamin B12 levels checked and report it to your doctor.
Warning Signs of Metformin
Metformin is not suggested for people who have conditions such as:
- Liver problems
- Kidney problems
- Allergic issues
- Alcohol users
- Cardiac patients
- Autoimmune disorders
- Breathing issues
If you have any health complications listed above, talk to your health care provider, they will suggest you a suitable drug.
It’s essential to keep in mind that:
- If you are using metformin, then inform your radiologist while undergoing an x-ray, MRI, CT scan because it may increase the risk of lactic acidosis due to the iodinated contrast agents used during the scan.
- Your doctor may recommend you to stop using metformin a few days before any surgery because general anesthesia can lower blood sugar levels and increase the risk of hypoglycemia.
Final Words
Metformin is a standard drug recommended for type 2 diabetes. It has serious risk factors and should be taken only when advised by your doctor. Taking the proper dose at the scheduled time every day is also essential.
If you take other drugs with metformin, talk to your doctor, to make sure it is safe.