Vitamin B6 Toxicity Symptoms: What to Look for and When to Call Your Doctor

Vitamin B6 is one of the B vitamins that your body needs to create energy. Although generally considered safe at recommended levels, very high intakes of vitamin B6 from supplements or pharmaceutical products can be dangerous.

So more is not better — stick to the recommended dosage of vitamin B6 as symptoms of toxicity can include minor skin reactions and severe neurological damage.

Vitamin B6, also called pyridoxine, acts as a coenzyme in the metabolism and utilization of carbohydrates, fats and proteins in your body, per the National Institutes of Health (NIH).

Involved in more than 100 enzyme reactions with a wide variety of functions, vitamin B6 benefits your immune system, protects your heart from cholesterol deposits and prevents the formation of kidney stones. Vitamin B6 is also required for normal brain function and development, per the NIH.

Your body can't store vitamin B6, so you have to get it from the food you eat. You can usually get enough vitamin B6 from your diet. In the U.S., many foods are fortified with B6, including cereals and protein bars.

Our bodies are able to absorb about 75 percent of the vitamin B6 we get from food, per a January 2015 ‌Advances in Nutrition‌ article. And meat sources have a higher bioavailability for B6 than plant-based sources, according to a January 2022 paper in ‌StatPearls‌. Some foods containing vitamin B6 include:

• Fish, including tuna and salmon
• Poultry, including chicken and turkey
• Meat, including organ meats
• Starchy vegetables such as potatoes
• Fruit, other than citrus

For optimum health, you should strive to meet the recommended daily allowance for vitamin B6 recommended by the NIH:

Although you can't really get too much vitamin B6 from food, larger doses from supplements have been shown to cause vitamin B6 overdose symptoms and can be toxic for children. For this reason, a maximum limit for vitamin B6 has been established by the NIH.

These are the max limits:

• For children, ages 4 to 8 years: 40 milligrams
• For children, ages 9 to 13 years: 60 milligrams
• For teens, 14 to 18 years: 80 milligrams
• For adults, 19 years and older: 100 milligrams

Vitamin B6 is available in multivitamins, in supplements combined with other B vitamins (referred to as B-complex) and as an individual supplement, commonly in the form of pyridoxine, per the NIH.

Vitamin B6 supplements can be taken in an oral pill, liquid capsule or chewable and sublingual (under the tongue, dissolvable) forms. Absorption of vitamin B6 from the various forms of supplements is similar and does not differ significantly from absorption from food sources.

Supplements taken orally are available without a prescription. Prescribed doses and injectable forms of this must be given by a healthcare professional.

Supplements typically range in dosage from 5 to 500 milligrams per tablet. Although excess vitamin B6 is normally excreted in your urine, long-term supplementation with amounts exceeding 50 milligrams per day for a long period of time may be harmful.

Daily doses of more than 1,000 milligrams of pyridoxine may lead to toxicity that could result in painful neurological symptoms, known as sensory neuropathy, according to Linus Pauling Institute at Oregon State University.

Some people have developed sensory neuropathies at daily doses of less than 500 milligrams (taken to treat carpal tunnel syndrome or premenstrual syndrome) over a period of months, per the Linus Pauling Institute. No evidence of sensory nerve damage has been reported with intakes below 200 milligrams of pyridoxine daily.

Along with its needed effects, vitamin B6 supplements may cause some unwanted outcomes. And it's possible to take too much B-complex. According to the Mayo Clinic, symptoms of vitamin B6 toxicity include:

• Nausea
• Heartburn
• Headache
• Drowsiness
• Mild numbness or tingling
• Reduced ability to sense pain or extreme temperatures
• Lack of muscle control
• Sensitivity to light

According to a July 2017 study in ‌Toxicology in Vitro‌, prolonged high doses of vitamin B6 leading to toxicity end up manifesting similar symptoms to a vitamin B6 deficiency. Vitamin B6 deficiency and toxicity often involve changes in the blood, skin, heart, gastrointestinal and neuronal cells.

The NIH warns that taking 1 to 6 grams of vitamin B6 for an extended period of 12 to 40 months can result in serious symptoms of toxicity, which include:

• Nerve toxicity that causes lack of muscle control and coordination
  
• Burning pain, numbness, tingling and weakness of the hands and feet
  
• Painful, unsightly skin patches or disfiguring skin lesions
  
• Sensitivity to light
  
• Gastrointestinal problems, including nausea and heartburn
  
• Decreased sense of touch, inability to feel vibration, pain or extreme temperatures

The severity of symptoms can be debilitating depending on the dosage‌.‌ An April 2018 study in ‌Neurology ‌suggests that symptoms can potentially reverse once you stop taking the B6 supplement.

Pyridoxine is used not only to treat and prevent vitamin B6 deficiency, but it's also prescribed for a number of conditions, including treating premenstrual syndrome, carpal tunnel syndrome and rheumatoid arthritis, according to Mount Sinai.

If you're at risk of a deficiency, talk to your doctor about taking a supplement. Some reasons you may need a supplement include:

• Restricted diet, such as vegetarianism
• Poor renal function or kidney disease
• Autoimmune disorders, such as rheumatoid arthritis, with inflammation causing low levels of vitamin B6
• Medical conditions that impair absorption, including Crohn's, celiac, inflammatory bowel disease, colitis
• Chronic alcohol dependence
• Reduction of stomach acid, especially in older individuals
• Certain genetic diseases, such as homocystinuria
• Recovery from surgery, such as for weight loss, gastric bypass or removal of part of the small intestine
• Obesity

Using medications that interfere with gastrointestinal absorption, including some anti-seizure drugs or proton pump inhibitors, may also require you to take a B6 supplement. Oral contraceptives can also deplete several B vitamins, according to the Cleveland Clinic.

Ask your doctor if it's safe for you to use vitamin B6 if:

• You have a medical condition
• You take medications or herbal products
• You are allergic to any drugs or foods

Tell your doctor if you have heart or kidney disease to make sure you can safely receive injectable vitamin B6.