Metformin is a prescription medication, so you need a healthcare provider to evaluate you and write a prescription before you can fill it at a pharmacy. There’s no way to buy it over the counter in the United States. The good news is that it’s one of the most affordable and widely available prescription drugs, often costing under $5 for a 30-day supply with a discount coupon.
The path to getting metformin depends on why you need it. It’s prescribed for type 2 diabetes, prediabetes, polycystic ovary syndrome (PCOS), and sometimes off-label for weight management. Here’s what to expect for each route.
Type 2 Diabetes: The Most Common Reason
Metformin has historically been the first-line treatment for type 2 diabetes, and it remains one of the most commonly prescribed medications for the condition. If your blood sugar levels are elevated but your A1C (a measure of average blood sugar over three months) is below 9%, your provider will likely start you on metformin alone. If your A1C is above 9%, metformin is typically prescribed alongside another medication.
To get a prescription, you’ll need blood work. Your provider will order a fasting blood glucose test, an A1C test, or both. A fasting glucose of 126 mg/dL or higher on two separate tests, or an A1C of 6.5% or above, confirms a type 2 diabetes diagnosis. At that point, metformin is a straightforward prescription for most people. Your doctor will also check your kidney function, since metformin is only safe to use when your kidneys are filtering blood at a certain rate. If your kidney filtration rate is 45 or above (measured in a routine blood test), you’re clear to take it at full doses.
Prediabetes: Getting It Before Diabetes Develops
If your A1C falls between 5.7% and 6.4%, you’re in the prediabetes range. Metformin is sometimes prescribed at this stage to prevent progression to full type 2 diabetes, particularly if you’re under 60, have a BMI of 35 or higher, or have a history of gestational diabetes. The landmark Diabetes Prevention Program study found that people taking metformin for prediabetes lost an average of 2.1 kg (about 4.6 pounds) and significantly reduced their risk of developing diabetes over the following years.
Not every provider prescribes metformin for prediabetes automatically. Lifestyle changes (diet and exercise) are considered the first approach. If you’ve been told you have prediabetes, you can ask your provider directly whether metformin makes sense for your situation. Being specific helps: mention your risk factors, family history, and whether lifestyle changes alone have been working.
PCOS: A Different Pathway
Metformin is widely used for polycystic ovary syndrome, particularly in women dealing with irregular periods or difficulty getting pregnant. It’s considered a strong first-line option for women with PCOS who aren’t ovulating, especially those with a BMI under 35. For women above that threshold, metformin tends to be less effective on its own.
If you suspect PCOS, your provider will typically evaluate you based on irregular or absent periods, signs of elevated androgens (like excess hair growth or acne), and sometimes an ultrasound showing ovarian cysts. Once diagnosed, you can discuss metformin as a treatment option. The typical dose for PCOS is 500 mg three times daily or 850 mg twice daily, and providers usually start low and increase gradually to reduce stomach upset.
Off-Label for Weight Loss
Some providers prescribe metformin off-label for weight management, particularly for people at high risk of metabolic complications who haven’t responded well to other approaches. It’s also used to prevent weight gain caused by certain psychiatric medications.
The weight loss effects are real but modest. In clinical studies of non-diabetic patients, results ranged from about 4 to 13 pounds over several months, with better results seen in people who stuck closely to their prescribed dose. One study found that highly adherent patients experienced about a 3.5% reduction in body weight over two years, while those with low adherence saw essentially no change.
Getting a prescription for weight loss alone can be trickier. Not every provider will prescribe metformin purely for this purpose, since newer medications like GLP-1 receptor agonists tend to produce more significant weight loss. Your best approach is to discuss your full metabolic picture, including any insulin resistance, elevated blood sugar, or difficulty losing weight despite consistent effort.
Where to Get Your Prescription
You have several options for the initial appointment. Your primary care doctor is the most straightforward route. An endocrinologist handles diabetes-specific care. For PCOS, a gynecologist or reproductive endocrinologist can prescribe it. Telehealth platforms also prescribe metformin for diabetes, prediabetes, and sometimes weight management, often with a faster turnaround than scheduling an in-person visit.
Regardless of which provider you see, expect to get blood work done. At minimum, this includes blood sugar or A1C testing and a kidney function panel. Some telehealth services let you use recent lab results if they’re less than a few months old.
Cost and Filling Your Prescription
Metformin is available as a generic, making it one of the cheapest prescription medications you can fill. The average retail price for a 30-day supply runs around $28, but with a free discount coupon from sites like GoodRx, you can pay as little as $2.75. Many insurance plans cover it with little to no copay, and some pharmacy discount programs include it on their $4 medication lists.
You can fill the prescription at any retail pharmacy. The immediate-release version is taken two or three times daily with meals, while the extended-release version is taken once daily. If cost is a factor, mention this to your provider, since the immediate-release generic tends to be the cheapest option.
What to Expect When You Start
Providers typically start you at a low dose, usually 500 mg once daily with a meal, and increase by 500 mg per week until you reach your target dose. This gradual approach exists for a practical reason: metformin commonly causes nausea, diarrhea, and stomach cramps in the first few weeks, and ramping up slowly makes these side effects far more manageable. Most people find the digestive issues settle down within a few weeks.
Taking metformin with food significantly reduces stomach problems. If the standard version still bothers you after a few weeks, the extended-release formulation is gentler on the digestive system and worth asking about. Your provider will likely recheck your blood work after two to three months to see how well the medication is working and adjust your dose from there.
One important safety note: metformin is contraindicated if your kidney function drops below a certain level. If your filtration rate is between 30 and 44, providers generally won’t start new patients on it, though existing users may continue at a reduced dose. Below 30, metformin should not be used at all. Your kidney function will be checked periodically as long as you’re on the medication.