Are Mouth Sores Caused by Muscle Building Supplements?

Mouth sores -- also called cold sores or fever blisters -- are lesions filled with fluid caused by a virus. The sores generally last 10 to 14 days and appear as painful red, raised areas of the skin near the mouth. You may also experience tingling or pain a day or two before sores appear. Although the herpes simplex virus 1 is the main cause of mouth sores, muscle-building supplements may play a role in both mouth sores and mouth ulcers, also called canker sores.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.


Arginine is a naturally occurring amino acid found in foods such as dairy, red meat and nuts. Arginine can increase secretion of the human growth hormone that helps to increase lean tissue, which is muscle and everything but fat. Bodybuilders may take the synthetic L-arginine from supplements to enhance muscle, though most people get sufficient arginine from food. L-arginine supplements may lead to mouth sores by triggering the herpes virus, according to the Mayo Clinic. The herpes simplex virus type 1 is typically the cause of cold sores whereas herpes simplex virus type 2 causes genital herpes; however, both types may cause sores on the face.

Vitamin C

Painful spots on your mouth could be mouth ulcers. Mouth ulcers are linked to vitamin C supplements 2. Vitamin C is ascorbic acid and too much acid can cause problems in your mouth. According to an article published on the "Daily Mail" website in September 2007, taking around 500 to 1,000 milligrams of vitamin C may cause mouth ulcers 2. Vitamin C may be beneficial to weightlifters, according to an article on 3. Large amounts of vitamin C can suppress the release of the hormone cortisone, which lowers testosterone levels and causes your body to use muscle for fuel.

Additional Effects

Muscle building supplements can cause adverse effects besides mouth sores that are not only unpleasant, but could sabotage your workouts. Human growth hormone is a supplement believed to enhance athletic performance and muscle mass, though neither claim has been proven. Taking HGH may cause muscle weakness, joint pain, fluid retention, carpal tunnel syndrome and cardiomyopathy. Arguably the most popular supplement with weight lifters is creatine. Taking creatine may give you short bursts of power and could cause weight gain that indicates an increase in muscle mass, but is likely to cause fluid retention. Creatine may cause muscle cramps, nausea and diarrhea.


If you are working out hard to build muscle, you may be overtraining and wearing yourself out. Training too much without allowing your body to rest can cause fatigue. Mouth ulcers often show up when a person is run down, according to the Daily Mail article. Work with your doctor or a personal trainer to modify your workout routine to avoid overtraining. It may help to work out fewer days per week, reduce your repetitions and sets or engage in shorter workouts. Eating a balanced diet may also help fight fatigue to reduce mouth ulcers.