What is Metanx? Uses, warnings & side effects

Updated May 14, 2025

Metanx is a prescription dietary supplement used to provide nutritional support in the treatment of diabetic nerve damage (diabetic neuropathy). The active ingredients in Metanx capsules are B vitamins: vitamin B9 (as methylfolate calcium), vitamin B6 (as pyridoxal-5-phosphate), and vitamin B12 (as methylcobalamin). Metanx also contains powdered algae as a source of omega-3 fatty acids. These nutrients help to improve circulation and nerve function in people with diabetes by blocking the chemical and oxidative processes that damage blood vessels. Metanx capsules are taken twice daily under the direction of a doctor.

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Metanx overview

BRAND NAMES:

  • Metanx

Generic Names:

  • L-Methylfolate (B9)-Algae-Methylcobalamin (B12)- Pyridoxal (B6)

Uses:

  • Supplies the body with B vitamins to help treat diabetic neuropathy.

Therapeutic Classes:

  • Vitamin B combination, nutritive agent, nutriceutical

Forms:

  • Capsule

How it’s taken:

  • By mouth

What is Metanx used for?

  • Metanx is a prescription supplement used for the dietary management of diabetic nerve damage.

What form(s) does Metanx come in?

  • Capsule

    • 3 mg methylfolate (B9)/35 mg pyridoxal (B6)/2 mg methylcobalamin (B12)/90 mg algae-S powder

What are common Metanx dosages?

  • For diabetic neuropathy: 2 capsules daily

Metanx images - What does Metanx look like?

  • Metanx
    3-90.314-2-35mg capsule

How to take Metanx

  • Use only under the supervision of a doctor.

  • Your doctor will tell you how much medicine to use. Do not use more than directed.

  • Carefully follow your doctor's instructions about any special diet.

  • Take one capsule in the morning and one at night.

    • You can also take two capsules at the same time as your daily dose.

  • Store Metanx capsules at room temperature, protected from light, heat, and moisture.

What to do if you miss a dose of Metanx

  • Take a missed dose as soon as you remember. You can take two capsules at the same time to make up for a missed dose.

  • Do not take more than two capsules per day.

Metanx contraindications - Who shouldn't take Metanx?

  • Do not take Metanx capsules if you have had an allergic reaction to any of its ingredients. 

  • All three of the active ingredients in Metanx have been known to cause mild or serious allergic or skin reactions. Metanx also contains milk and soy products

Metanx warnings

  • Before taking Metanx supplements, tell the doctor about all the medical conditions you have.

  • The doctor may need to perform regular exams and blood tests to monitor the effects of this medicine. Keep all appointments.

  • The folate in Metanx can hide the symptoms of vitamin B12 deficiency including pernicious anemia. In these cases, the only way to spot the deficiency is with regular blood tests.

Metanx interactions & what to avoid when taking Metanx

  • The active ingredients in Metanx have no known drug interactions that are serious or moderate.

  • Even so, make sure you tell the prescribing healthcare professional about all the prescription drugs, over-the-counter medications, and dietary supplements you are taking before starting Metanx.

Metanx side effects - How does Metanx make you feel?

Serious side effects

The only relevant side effects of Metanx that are serious are allergic or skin reactions. Talk to a doctor if you notice any signs of a hypersensitivity reaction, including:

  • Itching or hives, diffuse skin rash, swelling in your face or hands, swelling or tingling in your mouth or throat, feeling of swelling across the entire body 

Less serious side effects

  • Nausea

  • Vomiting

  • Abdominal pain

  • Loss of appetite

  • Acne

  • Sensitivity to sunlight

  • Liver dysfunction (elevated enzymes)

  • Headache

  • Sleepiness

  • Pain or tingling (in areas where the nerves are already numb such as the feet or hands)

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