Does metformin cause mouth sores? (3+ factors)

In this article, we will discuss whether metformin causes mouth sores. We will also discuss the mechanism through which metformin can cause mouth sores, the factors that can contribute to mouth sores, and how to manage mouth sores while taking metformin. 

Does metformin cause mouth sores? 

Metformin may cause mouth sores by potentially causing vitamin B12 deficiency but it has also shown effectiveness in treating conditions like Behcet’s disease which is characterized by mouth sores. 

Metformin has been associated with a deficiency of vitamin B12. The symptoms of vitamin B12 deficiency include fatigue, weakness of muscles, pale skin, sore red tongue, and mouth sores (1). 

Metformin is a biguanide agent primarily used to manage type 2 diabetes due to its hypoglycemic effects. It is typically used for long-term and long-term usage can lead to a deficiency of vitamin B12 which can cause mouth sores as a symptom. 

However, metformin is also known to have anti-inflammatory properties and has a potential therapeutic value in treating autoimmune inflammatory disorders like Behcet’s disease which result in painful mouth sores (2). 

If you experience a deficiency of vitamin B12 while taking metformin, you can experience mouth sores. If you experience this side effect, contact your healthcare provider. 

How does metformin cause mouth sores? 

Long-term treatment with metformin is associated with the deficiency of vitamin B12. This deficiency can cause mouth sores as a symptom. The deficiency can be caused by different mechanisms (3).

Metformin-induced vitamin B12 deficiency may be caused by alteration in the absorption of vitamin B12. Metformin can interfere with how vitamin B12 attaches to the cells of the ileum which impairs its absorption (3). 

Metformin can also change the motility of the small intestine leading to bacterial overgrowth and impairing the absorption of vitamin B12. Metformin may also change how the body uses bile acids impacting the circulation of vitamin B12 (3). 

The most plausible mechanism of metformin-induced vitamin B12 deficiency is its interference with the formation of the calcium-B12 complex which is needed for the absorption of vitamin B12 from the intestines (3). 

Through these mechanisms, metformin can result in vitamin B12 deficiency which causes mouth sores. Research suggests that 6-30% of the people taking metformin may experience vitamin B12 deficiency as a side effect (4).

What factors may contribute to metformin-induced mouth sores? 

Different factors may contribute to mouth sores which are as follows (5):

What is the role of metformin in treating mouth sores?

Although metformin can cause mouth sores as a result of vitamin B12 deficiency, studies have also explored its effectiveness in treating autoimmune inflammatory disorders due to its ability to reduce inflammation (2). 

One such disorder is Behcet’s disease which is characterized by the following symptoms: 

• painful mouth sores
• genital sores
• eye inflammation
• arthritis

Research suggests that such autoimmune diseases are caused by an imbalance of Treg/Th17, two types of immune cells. Metformin can restore this balance and can help manage Behcet’s disease (2). 

Research indicates that metformin can be effective in managing inflammatory diseases that can result in mouth sores (2). 

Thus, metformin can cause mouth sores as a side effect and on the other hand, can help to manage disorders that cause mouth sores as a symptom (2). 

What to do if metformin causes mouth sores? 

If you experience mouth sores while taking metformin, contact your healthcare provider. Your healthcare provider might check your serum vitamin B12 levels and prescribe supplements in case of deficiency (1).

Maintaining good oral hygiene is crucial to healing mouth sores. Brush your teeth daily and use a non-alcoholic mouthwash. Avoid hot, spicy, acidic, and salty foods, as they can irritate your mouth. Additionally, avoid tobacco and alcohol (5). 

Lifestyle modifications are important to manage mouth sores. Inadequate sleep, overworking, and extreme fatigue can also trigger mouth sores. Healthy nutrition, exercise, and rest can reduce the occurrence of mouth sores (5). 

Take metformin exactly as prescribed by the healthcare provider. Take it with meals to reduce the risk of side effects. If you are taking an immediate-release formulation, you can cut metformin tablets for ease of swallowing. 

Do not cut or crush the tablets if you are using an extended-release formulation of metformin. Contact your healthcare provider if you experience any unusual side effects. 

In my experience: 

As per my understanding, metformin may cause mouth sores as it can result in vitamin B12 deficiency and mouth sores are a common symptom of vitamin B12 deficiency. 

However, metformin is also known for its anti-inflammatory properties and has shown effectiveness in treating Behcet’s disease, an autoimmune disorder characterized by mouth sores, genital sores, and eye inflammation. 

If you experience mouth sores while taking metformin, contact your healthcare provider. Your healthcare provider may prescribe vitamin B12 supplements and suggest lifestyle modifications to manage metformin-induced mouth sores. 

References