Vitamin B6 is part of the B vitamin family and goes by several names: pyridoxine, pyridoxal, and pyridoxamine. Like other B vitamins, it dissolves in water rather than fat, which means your body doesn’t store much of it. You need a fairly regular intake from food or supplements.

What makes vitamin B6 worth paying attention to? It functions as a coenzyme in over 100 enzymatic reactions in your body. That’s not a number I just made up. Amino acid metabolism, neurotransmitter synthesis (including serotonin and dopamine), haemoglobin production, immune function, and glucose regulation all depend on having enough B6 around.

What happens when you don’t get enough vitamin B6?

True severe deficiency is uncommon in people eating varied diets. However, mild to moderate deficiency does occur, particularly in older adults, people who drink heavily, and those with certain malabsorption conditions.

If you’re wondering what deficiency actually looks like, the symptoms include:

Cracking and soreness at the corners of the mouth (angular cheilitis)
Inflammation of the tongue (glossitis)
Irritability and depression
Confusion and difficulty concentrating
Weakened immune function
Peripheral neuropathy in severe cases

The thing about B6 deficiency is that it rarely happens in isolation. People low in B6 are often low in other B vitamins too, which makes it tricky to attribute symptoms to any single nutrient.

Where do you get vitamin B6 from food?

Before reaching for supplements, it’s worth knowing that many common foods contain reasonable amounts of vitamin B6:

Poultry: Chicken and turkey breast
Fish: Tuna, salmon, and cod
Starchy vegetables: Potatoes and sweet potatoes (the skin contains quite a bit)
Non-citrus fruits: Bananas and avocados
Whole grains: Brown rice, oats, and fortified cereals
Legumes: Chickpeas and lentils
Beef liver (though most people aren’t eating much of this anymore)

The recommended daily allowance for adults is 1.3 mg for those under 50, rising to 1.5-1.7 mg for those over 50. Most people in developed countries get this amount from food alone.

What does the research say about vitamin B6 benefits?

I’ve gone through the clinical literature, and I should be upfront: the evidence for most B6 benefits is less impressive than supplement marketing would have you believe. That said, there are some areas where the research shows genuine promise.

1. Morning sickness during pregnancy

Nausea and vomiting affect somewhere between 50% and 90% of pregnant women, typically during the first trimester. For some women, it’s mild discomfort. For others, it’s debilitating enough to require medical intervention.

The American College of Obstetricians and Gynecologists actually recommends vitamin B6 as a first-line treatment for morning sickness. That’s notable because medical bodies don’t tend to recommend supplements without reasonable evidence.

A double-blind trial comparing vitamin B6 with ginger in 126 pregnant women found both helped reduce nausea and vomiting, though ginger appeared slightly more effective [1]. Another controlled study found that vitamin B6 combined with doxylamine (an antihistamine) significantly reduced symptoms compared to placebo [2].

The typical dose used in studies is 10-25 mg taken three times daily. Side effects appear minimal at these doses.

My honest take: this is probably the most evidence-supported use of vitamin B6 supplementation. The NHS acknowledges it as a potential treatment option, and it’s considered safe during pregnancy when used appropriately [3].

2. Premenstrual syndrome (PMS)

About 85% of menstruating women experience at least one PMS symptom in the days leading up to their period. Symptoms range from breast tenderness and bloating to mood swings, irritability, and depression.

The theory behind B6 for PMS relates to its role in neurotransmitter synthesis. Serotonin levels fluctuate with hormonal changes, and B6 is needed to produce serotonin from tryptophan.

A double-blind study of 76 university women found that combining vitamin B6 with calcium significantly improved both physical and psychological PMS symptoms compared to either supplement alone [4]. The combination appears more effective than B6 by itself.

A Cochrane review looked at nine trials involving vitamin B6 for PMS and concluded there was some evidence of benefit for overall symptoms and depression, but trial quality was generally poor [5].

Honest assessment: there’s something here, but the evidence isn’t overwhelming. If you’re going to try B6 for PMS, combining it with calcium seems sensible based on current research. Keep doses under 100 mg daily to avoid potential nerve problems.

Age-related macular degeneration (AMD) is a leading cause of vision loss in people over 60. It progressively destroys central vision by damaging the macula, the part of the retina responsible for sharp, detailed sight.

A large randomised trial following 5,442 women over 7.3 years found that daily supplementation with vitamin B6, folic acid, and vitamin B12 reduced the risk of AMD by 35-40% compared to placebo [6].

The proposed mechanism involves homocysteine. Elevated homocysteine levels in the blood are associated with increased AMD risk, and B vitamins help metabolise homocysteine. Lower homocysteine may mean less oxidative stress and better blood vessel function in the retina.

The catch? This was a combination of three B vitamins, so we can’t attribute the effect to B6 specifically. Still, if you’re at risk for macular degeneration, ensuring adequate intake of all B vitamins seems prudent.

4. Carpal tunnel syndrome

Carpal tunnel syndrome occurs when the median nerve gets compressed as it passes through the wrist. Symptoms include numbness, tingling, and weakness in the hand, particularly the thumb, index, and middle fingers.

There’s a long history of using vitamin B6 for carpal tunnel, dating back to the 1970s. The rationale is somewhat unclear, but some researchers have suggested that B6 deficiency might be more common in people with carpal tunnel, or that B6 might have some effect on nerve function.

One controlled study of 67 patients with mild to moderate carpal tunnel syndrome found that vitamin B6 supplementation over 3 months improved symptoms including pain frequency, numbness, weakness, and tingling [7].

However, a systematic review of the evidence concluded that while some trials showed benefit, the overall quality of evidence was low, and results were inconsistent [8].

My take: if you have carpal tunnel and want to try B6, it’s unlikely to cause harm at reasonable doses. But don’t expect miracles, and don’t delay proper medical treatment (wrist splints, corticosteroid injections, or surgery if needed) while experimenting with supplements.

5. Hand-foot syndrome from chemotherapy

Hand-foot syndrome (also called palmar-plantar erythrodysesthesia) is a side effect of certain chemotherapy drugs. It causes painful redness, swelling, and sometimes blistering on the palms and soles.

Vitamin B6 has been studied as a potential preventive treatment. The theory made some biological sense, leading to multiple trials.

Unfortunately, a systematic review and meta-analysis of 14 studies involving 1,570 patients found that prophylactic vitamin B6 did not significantly reduce the incidence or severity of hand-foot syndrome [9].

I should be honest here: this is one area where the initial promise didn’t hold up to rigorous testing. The evidence suggests B6 doesn’t help prevent this side effect. If you’re undergoing chemotherapy and experiencing hand-foot syndrome, talk to your oncologist about evidence-based management strategies.

Side effects and safety concerns

Vitamin B6 is water-soluble, which means excess amounts get excreted in urine rather than building up in fat tissue. However, this doesn’t mean you can take unlimited amounts safely.

Common side effects at normal doses

At typical supplemental doses (under 100 mg daily), side effects are uncommon but can include:

Nausea
Heartburn
Sensitivity to sunlight
Skin irritation
Headache

Nerve damage from high doses

The more serious concern with vitamin B6 is sensory neuropathy from chronic high-dose use. This typically occurs with doses above 200 mg daily taken for extended periods, though some cases have been reported at lower doses.

Symptoms of B6-induced neuropathy include:

Numbness and tingling in the hands and feet
Loss of coordination and balance
Difficulty walking
Reduced ability to sense temperature and pain

The NHS recommends that adults should not take more than 200 mg of vitamin B6 daily from supplements [3]. Many experts suggest an even more conservative limit of 100 mg daily for long-term use.

The good news is that symptoms usually improve after stopping high-dose B6, though recovery can take months to years in severe cases.

Safety precautions (3 contraindications)

1. Pregnancy and breastfeeding

While vitamin B6 is actually recommended for morning sickness, this should be done under medical supervision. The appropriate dose matters. The NHS advises pregnant women to get B6 from food sources where possible and to consult a healthcare provider before taking supplements [3].

During breastfeeding, high doses of B6 may reduce milk production in some women. Stick to amounts found in standard prenatal vitamins unless your doctor advises otherwise.

2. Drug interactions

Several medications interact with vitamin B6 in ways that matter clinically:

Levodopa: Vitamin B6 can reduce the effectiveness of levodopa (used for Parkinson’s disease) when levodopa is taken alone. However, this interaction doesn’t occur when levodopa is combined with carbidopa, which is how it’s typically prescribed now.

Phenytoin and other anti-seizure medications: High-dose B6 may reduce blood levels of these drugs, potentially reducing their effectiveness.

Certain antibiotics: Tetracyclines and similar antibiotics may have reduced absorption when taken with high-dose B6.

Chemotherapy drugs: Some chemotherapy agents may be affected by B6 supplementation.

If you’re taking any prescription medications, check with your pharmacist or doctor before adding B6 supplements.

3. Medical conditions requiring caution

People with certain conditions should be particularly careful with B6 supplementation:

Kidney disease: Impaired kidney function means B6 and its metabolites may accumulate, increasing the risk of toxicity at lower doses.
Neuropathy from other causes: If you already have nerve damage from diabetes or other conditions, B6 toxicity could worsen symptoms.
Parkinson’s disease: As mentioned above, B6 can interact with levodopa.

What about drugs that deplete vitamin B6?

Certain medications can interfere with B6 metabolism and may increase your requirements:

Oral contraceptives (birth control pills)
Isoniazid and other anti-tuberculosis drugs
Penicillamine (used for rheumatoid arthritis and Wilson’s disease)
Some anti-hypertensive medications
Theophylline (used for asthma)
NSAIDs with long-term use

If you’re taking any of these medications long-term, your doctor may recommend monitoring your B6 status or taking a low-dose supplement. This isn’t something to self-manage with high-dose supplements.

How much vitamin B6 should you take?

For most people, the answer is: whatever you get from food is probably enough.

If you do supplement, here are the generally accepted guidelines:

Recommended daily allowance: 1.3-1.7 mg depending on age and sex
Upper tolerable limit: 100 mg daily (conservative) to 200 mg daily (NHS recommendation)
Therapeutic doses: 10-25 mg three times daily has been used for morning sickness; 50-80 mg daily for PMS

Doses used in clinical trials for specific conditions often exceed the RDA but should remain below the upper tolerable limit to avoid nerve damage.

References

Chittumma P, et al. Comparison of the effectiveness of ginger and vitamin B6 for treatment of nausea and vomiting in early pregnancy: a randomized double-blind controlled trial. J Med Assoc Thai. 2007;90(1):15-20. PMID: 17621727
Shahraki S, et al. Comparison of ginger and vitamin B6 in relieving nausea and vomiting during pregnancy. Ayu. 2012;33(4):443-447. PMID: 24834091
NHS. Vitamin B6. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-b/
Masoumi SZ, et al. Effect of calcium-vitamin B6 on premenstrual syndrome: a double-blind randomised controlled trial. J Caring Sci. 2016;5(1):67-73. PMID: 26989667
Wyatt KM, et al. Efficacy of vitamin B6 in the treatment of premenstrual syndrome: systematic review. BMJ. 1999;318(7195):1375-1381. PMID: 10334745
Christen WG, et al. Folic acid, pyridoxine, and cyanocobalamin combination treatment and age-related macular degeneration in women: the Women’s Antioxidant and Folic Acid Cardiovascular Study. Arch Intern Med. 2009;169(4):335-341. PMID: 19237716
Talebi M, et al. The effect of vitamin B6 on clinical symptoms and electrodiagnostic results of patients with carpal tunnel syndrome. Adv Pharm Bull. 2013;3(2):283-288. PMID: 24312849
Ryan-Harshman M, Aldoori W. Carpal tunnel syndrome and vitamin B6. Can Fam Physician. 2007;53(7):1161-1162. PMID: 17872810
Chen M, et al. Efficacy of vitamin B6 in the prevention of palmar-plantar erythrodysesthesia syndrome: a systematic review and meta-analysis. Drugs R D. 2020;20(4):283-293. PMID: 33190278