What should you not mix with vitamin B6?

October 6, 2025 •

4 min read

According to the National Institutes of Health, vitamin B6 supplements can interact with several medications, potentially reducing the effectiveness of the drug or causing other complications. Knowing what you should not mix with vitamin B6 is essential for anyone taking supplements alongside prescription medication.

Quick Summary

Several medications, including some for Parkinson's disease, epilepsy, and chemotherapy, have clinically significant interactions with supplemental vitamin B6. These interactions can either diminish the drug's efficacy or cause other adverse effects, necessitating careful monitoring and consultation with a healthcare provider.

Key Points

Avoid B6 with Levodopa (without Carbidopa): Supplemental vitamin B6 can decrease the effectiveness of levodopa, a drug used for Parkinson's disease, by increasing its metabolism in the body.
Be cautious with chemotherapy drugs: When mixed with certain chemotherapy agents like altretamine, vitamin B6 might reduce the drug's therapeutic effectiveness.
B6 can affect anticonvulsants: Supplemental vitamin B6 can decrease the concentration of some anticonvulsants (e.g., phenytoin, phenobarbital), potentially leading to a loss of seizure control.
Manage B6 carefully with antibiotics: Antibiotics like cycloserine and isoniazid interact with B6, often causing a deficiency. Supplementation may be necessary but must be medically supervised.
Discuss all supplements with your doctor: Before adding any vitamin B6 supplement to your regimen, always consult a healthcare provider to ensure it does not negatively interact with your current medications.

Key Drug Interactions with Vitamin B6

While vitamin B6 (pyridoxine) is an essential nutrient found in many foods, supplemental doses can interfere with the way certain medications work in the body. These interactions can be complex and may affect medication efficacy or lead to adverse side effects. The following sections detail some of the most critical drug interactions to be aware of.

Parkinson's Disease Medications and Vitamin B6

Levodopa (Alone)

One of the most well-known and significant interactions is between vitamin B6 and levodopa, a medication used to treat Parkinson's disease. The risk primarily applies when levodopa is taken without carbidopa. Vitamin B6 can increase how quickly the body breaks down levodopa in the peripheral nervous system, reducing the amount that reaches the brain where it is needed. This can diminish the drug's therapeutic effects and worsen Parkinson's symptoms.

When levodopa is combined with carbidopa, as in medications like Sinemet, the carbidopa prevents this peripheral breakdown, allowing the combination to be taken with vitamin B6 supplements with less concern. However, patients should always consult their neurologist before adding any supplement to their regimen.

Chemotherapy Agents and Vitamin B6

Altretamine

Patients undergoing chemotherapy with drugs like altretamine (Hexalen) should be cautious with vitamin B6 supplementation. Taking vitamin B6 with altretamine might reduce the chemotherapy drug's effectiveness, especially when taken alongside another drug, cisplatin. A healthcare provider should be consulted regarding any supplements during cancer treatment.

Anticonvulsants and Epilepsy Medications

Phenytoin and Phenobarbital

For individuals with epilepsy, the combination of vitamin B6 supplements and anticonvulsant medications like phenytoin (Dilantin) and phenobarbital requires careful management. Supplemental pyridoxine can increase the metabolism of these drugs, potentially decreasing their concentration in the blood and leading to a loss of seizure control. This necessitates close monitoring by a physician.

Levetiracetam and Other AEDs

Conversely, some antiepileptic drugs (AEDs) can cause vitamin B6 deficiency. In the case of levetiracetam (Keppra), supplemental B6 has been investigated for its potential to reduce the medication's behavioral side effects, such as irritability. Research has shown that supplementation can significantly decrease the risk of discontinuing levetiracetam due to these side effects, highlighting the complex relationship between AEDs and vitamin B6.

Antibiotics and Tuberculosis Medications

Cycloserine

Cycloserine is an antibiotic used to treat tuberculosis, and it is known to interfere with vitamin B6 metabolism. The drug can create a functional vitamin B6 deficit, leading to side effects like seizures and peripheral neuropathy. Because of this, it is common for cycloserine to be co-administered with a vitamin B6 supplement to help mitigate these neurotoxic effects. However, this should only be done under strict medical supervision.

Isoniazid

Another tuberculosis medication, isoniazid (INH), can cause vitamin B6 deficiency by interfering with its metabolism and increasing excretion. Doctors often prescribe B6 supplementation alongside isoniazid to prevent peripheral neuropathy and other neurological side effects.

Amiodarone and Increased Photosensitivity

Amiodarone

Amiodarone (Cordarone), a medication used to treat heart rhythm problems, is known to increase sensitivity to sunlight. Taking vitamin B6 along with amiodarone can potentially increase the chances of skin reactions like sunburn, blistering, or rashes when exposed to the sun. Patients on this medication should ensure they use sunblock and wear protective clothing while outdoors.

Comparison of Key Vitamin B6 and Medication Interactions


Medication Category	Specific Drug Examples	Effect of B6 Supplementation	Recommended Action
Parkinson's Disease	Levodopa (without Carbidopa)	Decreases drug effectiveness	Avoid supplemental B6 unless directed by a doctor.
Chemotherapy	Altretamine	Reduces chemotherapy effectiveness	Avoid supplemental B6 during treatment.
Anticonvulsants	Phenytoin, Phenobarbital	Decreases drug concentration and effectiveness	Monitor closely; discuss B6 levels with a doctor.
Antibiotics (Tuberculosis)	Cycloserine, Isoniazid	Can worsen side effects (cycloserine) or is depleted by the drug (isoniazid)	Often co-administered to prevent deficiency and side effects under medical guidance.
Cardiac Medicine	Amiodarone	Increases photosensitivity	Use sun protection; discuss with a doctor.
Anticonvulsants	Levetiracetam	May reduce behavioral side effects	Discuss with a doctor; supplementation may be recommended.

Conclusion: Always Consult Your Healthcare Provider

While vitamin B6 is a crucial nutrient, its relationship with pharmaceuticals is complex. Some interactions, like that with levodopa, can be mitigated by combining drugs, while others, like with certain chemotherapy agents, require avoiding supplementation altogether. Furthermore, some medications deplete the body of B6, necessitating supplementation under a doctor's care. For these reasons, it is critically important to consult a healthcare provider or pharmacist before taking any over-the-counter vitamin B6 supplement, especially if you are on any other medications. This ensures your safety and the continued effectiveness of your treatment plan. The National Institutes of Health provides reliable information on vitamin-drug interactions that can serve as a helpful starting point for discussion with your doctor.

Frequently Asked Questions

You can take vitamin B6 with Parkinson's medication, but with an important distinction. If you are taking levodopa alone, B6 supplements should be avoided as they can reduce its effectiveness. However, if your medication is a combination of levodopa and carbidopa (like Sinemet), the interaction is prevented. Always consult your doctor before taking supplements.

Yes, vitamin B6 can interact with certain chemotherapy drugs. For example, taking vitamin B6 with altretamine may reduce its effectiveness. Patients undergoing cancer treatment should always discuss vitamin and supplement intake with their oncologist.

The interaction between vitamin B6 and epilepsy medication is complex. Supplemental B6 can decrease the effectiveness of some anticonvulsants like phenytoin, increasing seizure risk. On the other hand, certain antiepileptic drugs can cause B6 deficiency, and in some cases, B6 supplementation might be used to manage medication side effects. Your doctor should monitor and guide any supplementation.

It depends on the antibiotic. Some, like cycloserine and isoniazid, interfere with B6 metabolism and may cause a deficiency. In these cases, your doctor may recommend B6 supplementation to prevent side effects like nerve damage. This should only be done under a doctor's supervision.

Taking vitamin B6 with amiodarone, a heart medication, can increase your sensitivity to sunlight. This raises the risk of sunburn, rashes, and blistering on sun-exposed skin. Always wear sunblock and protective clothing when spending time outdoors.

Yes, chronic alcohol use is a known risk factor for vitamin B6 deficiency. Alcohol can interfere with B6 metabolism, making supplementation potentially necessary in individuals with alcohol dependency. Any supplementation should be discussed with a healthcare professional.

While uncommon, excessive intake of vitamin B6, typically from supplements over a long period, can lead to nerve damage (neuropathy) and other neurological problems. Discuss appropriate intake with your healthcare provider.