Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate. The effectiveness ratings for VITAMIN B6 are as follows:
- Seizures. Administering vitamin B6 intravenously (by IV) controls seizures in infants that are caused by vitamin B6 dependence.
- A condition in which the body makes abnormal red blood cells that build up iron (sideroblastic anemia). Taking it by mouth is effective for treating an inherited type of anemia called sideroblastic anemia.
- Vitamin B6 deficiency. Taking vitamin B6 by mouth is effective for preventing and treating deficiency.
Likely effective for…
- High levels of homocysteine in the blood (hyperhomocysteinemia). Taking it by mouth, usually with folic acid, is effective for treating high homocysteine levels in the blood.
Possibly effective for…
- Hardening of the arteries (atherosclerosis). As people age, their arteries tend to lose their ability to stretch and flex. Garlic and other ingredients seem to reduce this effect. Taking a specific supplement containing garlic, amino acids (part of proteins), and vitamins such as folic acid, vitamin B12, and vitamin B6 (Kyolic, Total Heart Health, Formula 108, Wakunga) seem to reduce symptoms of hardening of the arteries.
- Kidney stones. People with a hereditary disorder called type I primary hyperoxaluria have an increased risk of forming kidney stones. There is some evidence that taking it by mouth, alone or along with magnesium, or getting vitamin B6 injected into the vein, can decrease the risk of kidney stones in people with this condition. However, it does not appear to help people with other kinds of kidney stones.
- Morning sickness. Some research suggests that taking vitamin B6, usually as pyridoxine, improves symptoms of mild to moderate nausea and vomiting during pregnancy. The American College of Obstetrics and Gynecology considers it a first-line treatment for nausea and vomiting caused by pregnancy. Vitamin B6 plus the medication doxylamine is recommended for women who do not get better when treated with just vitamin B6. However, taking this combination is less effective than the medication ondansetron.
- Premenstrual syndrome (PMS). There is some evidence that taking vitamin B6 as pyridoxine by mouth can improve PMS symptoms including breast pain. The lowest effective dose should be used. Higher doses will increase the chance of side effects and are not likely to increase the beneficial effects.
- A movement disorder often caused by antipsychotic drugs (tardive dyskinesia). Taking it seems to improve movement disorders in people taking certain drugs for schizophrenia.
Possibly ineffective for…
- The decline in memory and thinking skills occurs normally with age. One study shows that taking vitamin B6, folic acid, and vitamin B12 might help prevent certain parts of the brain from deteriorating in elderly people. However, most research shows that taking it along with folic acid and vitamin B12 does not improve mental function in elderly people.
- Alzheimer disease. Early research suggests that a higher intake of vitamin B6 from supplements or as part of the diet is not associated with a reduced risk of Alzheimer’s disease in older people.
- Autism. Taking vitamin B6 along with magnesium does not seem to improve behavior in children with autism.
- Carpal tunnel syndrome. Although some early research suggests that taking vitamin B6 might relieve certain symptoms of carpal tunnel syndrome, most research suggests that this supplement does not benefit people with this condition.
- Cataracts. Research shows that taking it in combination with folic acid and vitamin B12 does not prevent cataracts in women. And it might increase the risk of having cataracts removed.
- An adverse skin reaction caused by cancer drug treatment (chemotherapy-induced acral erythema). Hand-foot syndrome is a skin reaction caused by cancer drugs. Taking vitamin B6 doesn’t seem to prevent this skin reaction in people treated with cancer drugs. There’s also concern that it might reduce how well the cancer drugs work.
- Non-cancerous growths in the large intestine and rectum (colorectal adenoma). Research shows that taking a combination of folic acid, vitamin B6, and vitamin B12 do not reduce the risk of colorectal polyps in women at high risk of heart disease.
- Weak and brittle bones (osteoporosis). Research shows that taking a combination of folic acid, vitamin B6, and vitamin B12 do not prevent broken bones in people with weak bones (osteoporosis).
Insufficient evidence to rate effectiveness for…
- Acne. Early research suggests that taking a product containing nicotinamide, azelaic acid, zinc, vitamin B6, copper, and folic acid, reduces lesion swelling and helps with the appearance of acne in adults and children.
- A procedure to open a blocked or narrowed blood vessel (angioplasty). Evidence on the benefits for preventing the re-blockage of blood vessels after angioplasty is inconsistent. Some evidence suggests that taking folic acid, vitamin B12, and vitamin B6 might reduce the re-blockage of blood vessels in people treated with balloon angioplasty. But other research shows no benefit in people who underwent coronary stenting.
- Asthma. The effectiveness of supplementation in children with asthma is unclear.
- Eczema (atopic dermatitis). Early research shows that taking it daily for 4 weeks does not reduce eczema symptoms in children.
- Attention deficit-hyperactivity disorder (ADHD). Early research shows that taking it by mouth, with or without high doses of other B vitamins, might help ADHD. However, research using high doses of both vitamin B6 and other vitamins seems to have no effect on ADHD symptoms.
- Cancer. Eating more foods that contain vitamin B6 has been linked with a lower risk of cancer. But taking vitamin B6 along with other vitamins and nutrients doesn’t prevent cancer in people with heart disease or kidney damage.
- Heart disease. Taking B vitamin combinations that include vitamin B6 does not seem to prevent death or heart attack in people with heart disease. But some recent data shows it might slightly lower the risk of stroke.
- Cavities. Taking vitamin B6 may reduce the risk of dental cavities during pregnancy.
- Depression. Eating more food that contains vitamin B6 has been linked with a lower risk of depression. Taking a supplement doesn’t seem to reduce depression symptoms in most people. But it might reduce the risk of developing depression in women taking birth control pills.
- Diabetes. Early research suggests that taking vitamin B6 improves blood sugar levels in women who are pregnant and have low levels. But not all research agrees.
- Menstrual cramps (dysmenorrhea). Early research suggests that taking vitamin B6 daily might reduce painful periods.
- Seizures in women with pre-eclampsia (eclampsia). Taking vitamin B doesn’t seem to reduce the risk of seizures during pregnancy.
- High blood pressure. Early research suggests that taking pyridoxine can lower blood pressure in people with high blood pressure.
- High levels of fats called triglycerides in the blood (hypertriglyceridemia). Early research suggests that taking vitamin B6 does not reduce high levels of blood fats called triglycerides. However, it might slightly reduce cholesterol levels.
- Insomnia. Some research shows that taking a product containing a protein called casein, plants called zizyphus and hops, as well as magnesium and vitamin B6, does not help people sleep better.
- Nerve damage caused by a drug for tuberculosis (isoniazid-induced neuropathy). Early research suggests that taking vitamin B6 daily might reduce nerve damage caused by isoniazid, a medication that is taken for tuberculosis.
- Breast-feeding. Early research suggests that taking vitamin B6 daily for about one week after giving birth does not stop breast milk production.
- Lung cancer. People who have higher blood levels of vitamin B6 seem to have a lower risk of lung cancer. This seems to be especially true for men and for people with a history of smoking. It’s unclear if taking vitamin B6 as a supplement can reduce the risk of lung cancer.
- Nausea and vomiting. Early research suggests that taking vitamin B6 does not reduce nausea or vomiting or improve symptoms of dehydration in children with an infection in the stomach or intestines. However, it might reduce the risk of nausea in women taking birth control pills.
- A pregnancy complication marked by high blood pressure and protein in the urine (pre-eclampsia). Taking vitamin B6 doesn’t seem to reduce the risk of pre-eclampsia.
- Preterm birth. Taking vitamin B6 doesn’t seem to reduce the risk of preterm birth.
- Seizures not caused by epilepsy. Early research suggests that taking vitamin B6 daily for 12 months does not reduce the risk of seizures caused by a high fever in children.
- Stroke. Taking B vitamin supplements that include vitamin B6 might slightly reduce stroke risk in people with heart disease. But it’s unknown which combination of B vitamins has the most benefit.
- Nerve damage caused by the drug vincristine. One report suggests that vitamin B6 might help reverse nerve damage caused by the chemotherapy drug vincristine. Research is needed to confirm these results.
- Down syndrome.
- Kidney problems.
- Long-term swelling (inflammation) in the digestive tract (inflammatory bowel disease or IBD).
- Lyme disease.
- Muscle cramps.
- Night leg cramps.
- Rheumatoid arthritis (RA).
- Other conditions.
More evidence is needed to rate vitamin B6 for these uses.
Side Effects Of Vitamin B6
- When taken by mouth: LIKELY SAFE for most people when used appropriately. Taking vitamin B6 in doses that do not exceed 100 mg per day is generally considered to be safe. Vitamin B6 is POSSIBLY SAFE when taken in doses less than 500 mg per day. In some people, vitamin B6 might cause nausea, vomiting, diarrhea, stomach pain, loss of appetite, headache, tingling, sleepiness, and other side effects. POSSIBLY UNSAFE when taken by mouth in doses of 500 mg or more daily, long-term. High doses, especially 1000 mg or more per day, might cause brain and nerve problems.
- When given by IV: Vitamin B6 is LIKELY SAFE when given by IV under medical supervision for uses approved by the FDA.
- When given as a shot: LIKELY SAFE when given as a shot into the muscle under medical supervision in amounts approved by the FDA. Using large doses of vitamin B6 as a shot into the muscle is POSSIBLY UNSAFE. It might cause muscle problems.
Warnings & Precautions
- Pregnancy: Vitamin B6 is LIKELY SAFE for pregnant women when taken under the supervision of their healthcare provider. It is sometimes used in pregnancy to control morning sickness. But high doses are POSSIBLY UNSAFE. High doses can cause newborns to have seizures.
- Breast-feeding: LIKELY SAFE for breast-feeding women when used in amounts not larger than 2 mg per day (the recommended dietary allowance). Avoid using higher amounts. Not enough is known about the safety of vitamin B6 at higher doses in breastfeeding women.
- Procedures to widen narrowed arteries (angioplasty). Using vitamin B6 along with folic acid and vitamin B12 intravenously (by IV) or by mouth might worsen narrowed arteries. It should not be used by people recovering from this procedure.
- Weight loss surgery. Taking a vitamin B6 supplement is not needed for people that have had weight loss surgery. And taking too much might increase the chance of side effects such as nausea, vomiting, and browning skin.
- Diabetes. Using a combination of vitamin B6, folic acid, and vitamin B12 might increase the risk of cancer in people with diabetes and a recent stroke. Vitamin B6 should not be used by patients with diabetes that have had a recent stroke.
Vitamin B6 Dosage
The following doses have been studied in scientific research:
- For a condition in which the body makes abnormal red blood cells that build up iron (sideroblastic anemia): Initially, 200-600 mg is used. The dose is decreased to 30-50 mg per day after an adequate response.
- For vitamin B6 deficiency: In most adults, the typical dose is 2.5-25 mg daily for three weeks then 1.5-2.5 mg per day thereafter. In women taking birth control pills, the dose is 25-30 mg per day.
- For high levels of homocysteine in the blood (hyperhomocysteinemia): For reducing high levels of homocysteine in the blood after meals, 50-200 mg of vitamin B6 has been taken alone. Also, 100 mg has been taken in combination with 0.5 mg of folic acid.
- For hardening of the arteries (atherosclerosis): A specific supplement (Kyolic, Total Heart Health, Formula 108, Wakunga) containing 250 mg of aged garlic extract, 100 mcg of vitamin B12, 300 mcg of folic acid, 12.5 mg of vitamin B6, and 100 mg of L-arginine daily for 12 months has been used.
- For kidney stones: 25-500 mg of vitamin B6 has been used daily.
- For morning sickness: 10-25 mg taken three or four times per day has been used. In people who don’t respond to vitamin B6 alone, a combination product containing vitamin B6 and the drug doxylamine (Diclectin, Duchesnay Inc.) is used three or four times per day. Also, another product containing 75 mg of vitamin B6, 12 mcg of vitamin B12, 1 mg of folic acid, and 200 mg of calcium (PremesisRx, KV Pharmaceuticals) is used daily.
- For symptoms of premenstrual syndrome (PMS): 50-100 mg is used daily, alone or along with 200 mg of magnesium.
- For treating a movement disorder often caused by antipsychotic drugs (tardive dyskinesia): 100 mg per day has been increased weekly up to 400 mg per day, given in two divided doses.
INJECTED INTO THE MUSCLE:
- A condition in which the body makes abnormal red blood cells that build up iron (sideroblastic anemia): 250 mg of vitamin B6 daily, reduced to 250 mg weekly once an adequate response is achieved.
- For kidney stones: Up to 20 mg/kg daily in children aged 5 years and up.
INJECTED INTO THE VEIN OR MUSCLE:
- For seizures: 10-100 mg is recommended for seizures in newborns who are dependent on vitamin B6.
- The daily recommended dietary allowances (RDAs) are: Infants 0-6 months, 0.1 mg; Infants 7-12 months, 0.3 mg; Children 1-3 years, 0.5 mg; Children 4-8 years, 0.6 mg; Children 9-13 years, 1 mg; Males 14-50 years, 1.3 mg; Males over 50 years, 1.7 mg; Females 14-18 years, 1.2 mg; Females 19-50 years, 1.3 mg; Females over 50 years, 1.5 mg; Pregnant women, 1.9 mg; and breast-feeding women, 2 mg. Some researchers think the RDA for women 19-50 years should be increased to 1.5-1.7 mg per day. The recommended maximum daily intake is Children 1-3 years, 30 mg; Children 4-8 years, 40 mg; Children 9-13 years, 60 mg; Adults, pregnant and breast-feeding women, 14-18 years, 80 mg; and Adults, pregnant and breast-feeding women, over 18 years, 100 mg.
Consult your doctor or pharmacist.
All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.