Who should avoid niacinamide? A guide to safe usage

October 1, 2025 •

4 min read

While niacinamide is celebrated for its skin and health benefits, it is not suitable for everyone, particularly in oral supplement form.

Understanding who should avoid niacinamide is crucial to prevent adverse reactions and ensure your wellness routine is safe and effective.

Quick Summary

Individuals with certain medical conditions, like severe liver disease, gallbladder problems, or active ulcers, should avoid oral niacinamide, as should kidney dialysis patients and those with very sensitive skin or rosacea when using high topical concentrations.

Key Points

Severe Liver Disease: Individuals with severe liver disease or damage should not take high-dose oral niacinamide supplements due to the risk of worsening liver problems.
Stomach and Intestinal Ulcers: People with active ulcers should avoid niacinamide supplements, as the substance can irritate and exacerbate the condition.
Kidney Dialysis Patients: Those on kidney dialysis should not take niacinamide supplements, as it may cause low platelet levels in this population.
Sensitive or Rosacea-Prone Skin: Individuals with sensitive skin or rosacea should start with low-concentration topical niacinamide and patch test, as high concentrations ( >5-10%) can cause irritation.
Certain Medications: Oral niacinamide can interact with blood thinners, certain liver-metabolized drugs (like carbamazepine), and diabetes medication, increasing risk or reducing efficacy.
Gout History: People with a history of gout should be cautious with high doses of oral niacinamide, as it may trigger a flare-up.

Medical Conditions That May Conflict with Oral Niacinamide

While topical niacinamide is generally well-tolerated, oral supplements at high doses can present risks for certain individuals. It is critical to consult a healthcare provider before beginning any new supplement regimen, especially if you have pre-existing health conditions.

Liver and Gallbladder Disease

Patients with liver or gallbladder issues should exercise caution with oral niacinamide, as it may worsen symptoms. High doses, in particular, have been linked to potential liver damage. In severe cases of liver disease, oral niacinamide is strongly discouraged.

Kidney Issues and Dialysis

For individuals undergoing kidney dialysis, oral niacinamide is not recommended. Some studies suggest it can increase the risk of low platelet levels in these patients. Given this specific risk, medical guidance is essential.

Stomach or Intestinal Ulcers

People with active peptic, stomach, or intestinal ulcers should avoid niacinamide, as it can aggravate the condition. The supplement may cause gastrointestinal upset, exacerbating ulcer-related symptoms.

Diabetes

Oral niacinamide might affect blood sugar levels, potentially causing an increase. Those with diabetes should monitor their blood sugar carefully if taking niacinamide supplements and discuss it with their doctor to manage any potential changes.

Gout

Large doses of niacinamide may trigger a gout flare-up. Individuals with a history of gout should be cautious and consult their physician before using high-dose oral supplements.

Allergies

Niacinamide can sometimes release histamine, the chemical responsible for allergic symptoms, potentially worsening allergies. If you have a history of allergies, especially to ingredients in a specific product, check labels and consult a doctor.

Sensitive Skin and Topical Niacinamide

Even topical niacinamide, often praised for being gentle, can cause issues for some skin types, particularly in higher concentrations.

Rosacea and Compromised Skin Barriers

Individuals with rosacea-prone or highly sensitive skin should approach niacinamide with caution. While its anti-inflammatory properties can be beneficial for some, others may experience redness, burning, or stinging, especially when using high-concentration products (over 5-10%). It is always best to start with a lower concentration and perform a patch test.

High Concentrations

As detailed in an article in the journal Antioxidants, while niacinamide is excellent for skin health, concentrations above 10% are often unnecessary and can increase the risk of irritation, even in non-sensitive skin. Most studies showing benefits use concentrations between 2% and 5%. Higher potency does not always mean better results and can lead to adverse reactions.

Potential Drug Interactions

Certain medications can interact negatively with niacinamide, either by altering how the body processes the drug or by compounding specific effects. Always inform your healthcare provider about all supplements you are taking.

Blood-Clotting Medications

Niacinamide supplements may slow blood clotting. Combining it with anticoagulant or antiplatelet drugs, such as warfarin, heparin, or aspirin, can increase the risk of bleeding and bruising.

Medications Processed by the Liver

Niacinamide can affect how quickly the liver breaks down certain medications, such as carbamazepine (Tegretol) and primidone (Mysoline), which could amplify the effects of these drugs. The combination of high-dose niacinamide with other hepatotoxic drugs can also increase the risk of liver damage.

Diabetes Medications

Because niacinamide can raise blood sugar levels, it may reduce the effectiveness of diabetes medications. Close monitoring is needed for individuals taking both.

Oral vs. Topical Niacinamide: A Comparison


Condition	Oral Niacinamide Risks	Topical Niacinamide Risks
Liver Issues	Can worsen symptoms and cause damage, especially in high doses.	Generally safe; no systemic liver effect.
Sensitive Skin / Rosacea	Less of a concern, but high doses may trigger systemic reactions.	Potential for irritation, redness, burning, particularly with higher concentrations ( >5-10%).
Ulcers	Can aggravate symptoms; should be avoided.	No known risk.
Kidney Dialysis	May lower platelet levels; should be avoided.	No known risk.
Diabetes	May increase blood sugar; requires careful monitoring.	No known risk.
Drug Interactions	Potential interactions with blood thinners, liver-metabolized drugs, and diabetes meds.	Minimal risk of systemic drug interactions.
Gout	High doses may worsen symptoms; caution advised.	No known risk.

Considerations Before Using Niacinamide

Even if you don't have a specific medical condition, it's wise to consider a few precautions before integrating niacinamide into your routine, especially with supplements.

Patch Testing for Topical Use

If you have sensitive or rosacea-prone skin, always perform a patch test when trying a new topical niacinamide product. Apply a small amount to a discreet area (like your inner arm) and wait 24-48 hours to check for any adverse reactions like redness or itching. This is particularly important for products with higher concentrations.

Dosage Matters

For oral supplements, adhering to recommended daily amounts is key. Doses exceeding 3 grams per day can lead to more serious side effects, such as liver issues or high blood sugar. For topical use, starting with a lower concentration (2-5%) is recommended before moving to higher ones if needed.

Pregnancy and Breastfeeding

While niacinamide is generally considered safe in recommended amounts during pregnancy and breastfeeding, it's always best to consult a healthcare provider before taking any new supplement.

Conclusion

While a highly beneficial ingredient for many, understanding who should avoid niacinamide is a critical step for responsible self-care. Those with specific medical conditions—particularly severe liver disease, active ulcers, or on kidney dialysis—should steer clear of oral supplements. Individuals with sensitive skin or rosacea should exercise caution with high-concentration topical products and always patch test. By being aware of these contraindications and discussing them with a healthcare professional, you can safely enjoy the benefits of niacinamide or find suitable alternatives for your unique health needs.

Disclaimer: This article provides general information and is not a substitute for professional medical advice. Always consult a healthcare provider regarding your health concerns.

For more in-depth information on the functions and applications of niacinamide, see the comprehensive review on the National Institutes of Health website.

Frequently Asked Questions

You should avoid oral niacinamide supplements if you have severe liver disease, gallbladder problems, kidney failure requiring dialysis, active stomach ulcers, or gout. You should also be cautious and consult a doctor if you have diabetes or are on specific medications.

Yes, but with caution. While it's often gentle, individuals with sensitive skin or rosacea may experience irritation, especially with high concentrations. It's best to start with a low percentage (2-5%) and perform a patch test first.

Oral niacinamide can interact with medications that slow blood clotting (anticoagulants/antiplatelets), drugs metabolized by the liver (like carbamazepine and primidone), and diabetes medications. Always consult a doctor if you are taking any of these.

While generally considered safe in recommended amounts, it's always prudent to speak with your healthcare provider before taking any new supplement during pregnancy or while breastfeeding.

No, topical niacinamide is much less likely to cause systemic issues, as it's not absorbed in large amounts into the bloodstream. The primary risk is localized skin irritation, particularly with higher concentrations.

Yes, in some cases. Niacinamide can cause the release of histamine, which might worsen allergic symptoms. If you have known allergies, discuss using niacinamide with your doctor and check for any contraindications.

Concentrations of 2-5% are generally effective and well-tolerated by most skin types. Higher concentrations (10% or more) can increase the risk of irritation, especially for sensitive skin.