Does metformin cause hair loss?

Worried about metformin causing hair loss? Learn what could be causing hair loss during your metformin treatment and methods for hair loss recovery.

By Georgia C. Yalanis, MD | Sep. 22, 2022 Medically reviewed by Keith Gardner, R.Ph.

Worried about your diabetes medications causing hair loss? Or, can metformin actually help with certain types of alopecia? Metformin hydrochloride is a prescription drug available as an immediate or extended-release tablet that is used in conjunction with a healthy diet, weight loss, and exercise to treat Type 2 diabetes mellitus. Metformin is considered the first-line medication used by healthcare professionals to safely and effectively lower high blood sugar levels. While metformin itself is not associated with hair loss, certain conditions metformin is used to treat, including polycystic ovary syndrome PCOS and Type 2 diabetes, may cause hair to fall out or thin in certain individuals. But, good news! There is new scientific evidence that suggests metformin may be able to help stimulate hair growth.

Does metformin cause hair loss?

The simple answer is no, metformin does not cause hair loss. But, the conditions metformin is used to treat are well-known to be associated with hair loss.

In general, hair loss can occur for the following reasons:

As a medication side effect,
From normal, age-related or hormonal causes,
Secondary to systemic disease states or health conditions that affect androgens (male sex hormones), and
Pathologic alopecia, which can occur for a variety of reasons.

Hair loss from Vitamin B12 and folate deficiency

There is evidence that long-term use of metformin may be associated with folate (vitamin B9) and vitamin B12 deficiency secondary to intestinal malabsorption of these essential vitamins. In clinical studies and medical reviews, individuals taking metformin demonstrated 9-52% lower levels of vitamin B12 than individuals taking a placebo and lower serum folate compared to control subjects.

Vitamin B12 is necessary for the synthesis of DNA, proper neurological function, and red blood cell function. Vitamin B12 is also a cofactor for the synthesis of close to 100 substrates including DNA, RNA, and proteins, with deficiency in vitamin B12 well-known to cause anemia and neuropsychiatric symptoms.

Folate is a coenzyme required for the synthesis of nucleic acids (DNA and RNA) and the metabolism of amino acids (the building blocks of protein). Folate is primarily acquired through the diet, with deficiency related to poor diet, alcoholism, or a malabsorptive state (i.e., a disorder that prevents your body from effectively absorbing nutrients from your food) as may be seen in individuals taking metformin.

Hair follicles are extremely vascular with small networks of blood vessels surrounding the follicular bulb. Hair follicles are also considered highly metabolic, having a rapid and predictable growth cycle. The role of vitamin B12 and folate in nucleic acid production would suggest they have a significant role in hair growth however, there is limited definitive data demonstrating this is the case.

In a study of individuals with alopecia areata (AA), a type of immune system mediated hair loss, mean red blood cell folate concentrations were lower in individuals with AA than controls. In another study involving individuals who had telogen effluvium (TE), a temporary and diffuse hair loss from excessive shedding, 2.6% of individuals demonstrated B12 but not folate deficiency. It is important to note that both of those studies were small, and there is inconclusive evidence in the medical literature as to the exact effect and role vitamin B12 and folate play in hair loss.

While recommendations vary among institutions and academic societies, individuals taking metformin for longer than four months should speak with their healthcare provider about having their folate and/or vitamin B12 levels checked.

Metformin-associated hair growth

There is emerging data suggesting that topical use of metformin can improve cutaneous wound healing, including potentially regenerating the hair follicle. In early data released from an in vitro study aiming to characterize the mechanism behind metformin’s ability to regrow hair, scientists demonstrated that metformin stimulates the activity of several biomarkers related to hair growth and improves the survival rate of transplanted hair follicles. While more data is needed to further characterize and promote the use of topical metformin to regrow hair, for many, this could be considered one of the more desirable side effects of metformin use.

Other causes of hair loss during metformin treatment

Hair loss from PCOS

Polycystic ovary syndrome (PCOS) is a hormonal condition where women experience menstrual irregularity, infertility, obesity, acne, and excess hair growth in a male-pattern as a result of enlarged, cystic ovaries that overproduce androgens. While the exact cause of PCOS is unknown, there are some genetic components and most women with PCOS have insulin resistance, which is known to be related to the overproduction of testosterone in this condition.

Hormonal imbalance in women that is characterized by abnormal androgen levels or elevated testosterone can lead to a type of hair loss called female androgenetic alopecia (FAGA). In FAGA, there is diffuse hair thinning over the central scalp, with an intact frontal hairline. The frequency of this condition occurring increases with age after puberty, and approximately one-third of women with female androgenetic alopecia also have abnormal androgen hormone levels. Thankfully, FAGA is a medical condition that progresses slowly and can be stopped or corrected if caught early.

Hair loss from Type 2 diabetes mellitus

Type 2 diabetes mellitus is a condition where blood glucose is too high and the cells of the body are resistant to insulin. Metformin is effective at lowering blood glucose, lowering hemoglobin A1c (a long-term marker of elevated blood glucose levels), improving cardiovascular mortality, and reducing cancer burden in individuals with Type 2 diabetes. Metformin exerts its glucose-lowering effects by decreasing hepatic glucose production, increasing insulin-mediated suppression of glucose production, and improving glucose uptake by peripheral tissues.

According to Nancy Mitchell, RN, a geriatric nurse with decades of experience treating individuals with diabetes,

“Elevated blood glucose damages blood vessels that supply hair follicles with oxygen and nutrients needed for growth. Diabetes affects our blood supply in a similar way that nicotine does in cigarette smokers. High blood sugar causes the vessels to stiffen and narrow. Starved hair follicles don’t receive the nourishment they need to repair and continue thriving. That’s why hair loss is relatively common among diabetics.”

Nancy additionally noted that, “Diabetes also affects estrogen levels, especially in women. And, decreased estrogen is associated with weakening and thinning of hair strands.”

The experts are all in agreement on this one: metformin, insulin, and other medications that are used to treat diabetes are not direct causes of hair loss in most diabetic patients. Just remember to take your supplements if they are needed!

Metformin hair loss recovery

There are many treatment options available for individuals who notice their hair fall out or start to thin. Deciding which options are best for you will depend on the type of hair loss occurring and recommendations from your healthcare provider.

Follow medical advice. When taking any prescription medication it is important to follow medical advice and take your medications exactly as prescribed. If you are wanting to begin a treatment for hair loss, be sure to speak with your healthcare provider to make sure your hair loss treatments do not interfere with any of your medications.
Intervene early. If you notice your hair beginning to thin or fall out, seek help early. The earlier diabetic-associated hair loss is noticed, the greater the chance of stopping the hair loss and regrowing hair.
Maintain a healthy diet. A well-balanced diet is necessary to obtain adequate micronutrients. Micronutrients are necessary for healthy development of the hair follicle, promotion of the hair cycle, and strengthening immune defense mechanisms that may be responsible for certain types of alopecia.
Consider taking vitamin B12 and folate supplements. Long-term metformin use is associated with decreased intestinal absorption of vitamin B12 and folate which are essential vitamins that must be acquired through diet. Vitamin B12 in the amounts found in most vitamin B12 supplements may not be adequate supplementation for severe vitamin B12 deficiency. Some healthcare providers may recommend vitamin B12 injections for severely deficient individuals. Vitamin B12 is relatively safe with a low potential for toxicity, so there is no upper limit on the amount that can be taken. Folate can safely be supplemented at a dosage of 400-1000 mcg per day.
Consider using over-the-counter minoxidil. Minoxidil is a topical preparation available as a liquid, spray, or foam made for daily use. It is available in several concentrations and is sold as a generic or under the brand name Rogaine for men and women. Minoxidil has a very well-defined safety and efficacy profile and is used in the management of several types of hair loss.
Use supplements biotin containing with caution. There are many supplements available that claim to stop hair loss or regrow hair quickly. Many of these supplements contain biotin, a B vitamin that is involved in a variety of metabolic processes. Notably, biotin is also used in many blood tests and chemical assays. When biotin is circulating in the blood above physiological levels due to supplementation, these laboratory tests will give back incorrect results due to biotin interference. Make sure you inform your healthcare provider about biotin supplementation before you have diagnostic laboratory procedures.

Talk to your healthcare provider about prescription medications like finasteride. Propecia is the brand name for the 5-alpha reductase inhibitor, finasteride. Finasteride is FDA-approved to treat male pattern baldness in men only. This medication is associated with undesirable sexual side effects, so it recommended to carefully weigh the risks and benefits before beginning treatment with Propecia.

Try an at-home hair growth laser. There are several cap devices that use low-level light/laser therapy (LLLT) to stimulate hair growth. Studies have conclusively shown these devices to significantly increase hair density. They are expensive though, so brace yourself before you shop.
Or, ask about platelet-rich plasma (PRP) with microneedling. While the exact microneedling mechanism of action is yet to be determined, we know that tissue microinjury can stimulate re-vascularization and promote the tissue healing cascade. Studies examining scalp microneedling for hair loss have demonstrated significantly more hair growth with microneedling when compared to even minoxidil.
Use topical rosemary oil. Rosemary essential oil applied to the scalp and massaged in has shown to cause a significant increase in hair count and decrease in scalp itching after six months of use.