Drug & supplement interaction

Bismuth Nitrate + Cephalexin

Cephalexin brand names: Keflex, Keftab, Cephalex, Lexin.

No Known Interaction
The bottom line No known interaction

We found no known interaction between Bismuth Nitrate and Cephalexin in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Bismuth Nitrate and Cephalexin

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Cephalexin and Bismuth Nitrate in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

Worth understanding: our licensed dataset holds no drug-interaction record for Bismuth Nitrate at all — not against Cephalexin, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Bismuth Nitrate safety at a glance

Bismuth Nitrate overall Use caution Bismuth nitrate is not a standard supplement and can pose toxicity risks, so it should only be used under professional guidance.
Pregnancy Avoid There is not enough safety information, so it is best avoided during pregnancy.
Breastfeeding Avoid Safety while breastfeeding is unknown, so avoid use.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Cephalexin and Bismuth Nitrate? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Bismuth Nitrate and Cephalexin May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. 3 of them are worth acting on rather than waiting out — marked below.

  • Confusion Worth acting on Additional detail

    Bismuth Nitrate

    “Orally, bismuth nitrate may cause headache. Long-term use of bismuth nitrate has been associated with bismuth encephalopathy. One report describes a patient who developed confusion, restlessness, convulsions, hypertonia, hypoventilation, and fever after taking 30-40 grams of bismuth nitrate daily for 10-20 years to treat stomach troubles. The patient was comatose upon admission to the hospital.”

    Bismuth Nitrate · Natural Medicines adverse-effect record, reported in cluster headache.

    3 sources cited
    1. 100547. Bismuth nitrate; MSDS No. B3396 [Online]; Mallenckrodt Baker: Phillipsburg, NJ, December 8, 1996. https://hazard.com/msds/mf/baker/baker/files/b3396.htm (accessed December 27, 2019).
    2. 100540. - Jaeger A, Kopferschmitt J, Sauder Ph, Flesch F, Tournoud C. Diagnosis in clinical toxicology. In: Bolt HM, de Wolff FA, Henderson PT (eds) Medical Toxicology. Archives of Toxicology (Supplement). Berlin/Heidelberg, Germany: Springer-Verlag; 1992:29-39. PubMed
    3. 100550. Von Bose MJ, Zaudig M. Encephalopathy resembling Creutzfeldt-Jakob disease following oral, prescribed doses of bismuth nitrate. Br J Psychiatry. 1991;158:278-80. PubMed

    Cephalexin

    Listed in the ADVERSE REACTIONS section of the FDA label for Cephalexin. Read the label on DailyMed ›

  • Seizures Worth acting on Additional detail

    Bismuth Nitrate

    “Orally, bismuth nitrate may be converted to nitrites in the intestines, which may cause methemoglobinemia. Symptoms may include shortness of breath, cyanosis, headache, fatigue, changes in mental status, dizziness, and discoloration of the skin. In severe cases, dysrhythmias, convulsion, coma, or death may occur.”

    Bismuth Nitrate · Natural Medicines adverse-effect record, reported in cluster headache.

    2 sources cited
    1. 100547. Bismuth nitrate; MSDS No. B3396 [Online]; Mallenckrodt Baker: Phillipsburg, NJ, December 8, 1996. https://hazard.com/msds/mf/baker/baker/files/b3396.htm (accessed December 27, 2019).
    2. 101508. Raafat BM, Samir WA, Khader MH. Met-Hemoglobin concentration reduction and methemoglobin reductase enhancement after applying of alpha-tocopherol and selenium combination as a radio protector against ionizing radiation exposure. Wulfenia J. 2012;19(10):37

    Cephalexin

    Listed in the ADVERSE REACTIONS section of the FDA label for Cephalexin. Read the label on DailyMed ›

  • Kidney problems Worth acting on Additional detail

    Bismuth Nitrate

    “Orally, bismuth nitrate may cause loss of appetite, headache, methemoglobinemia, or kidney damage. Chronic use of bismuth nitrate may cause black spots on the gums, bad breath, salivation, and a "bismuth line." In rare cases, chronic use of bismuth may cause bismuth encephalopathy. Orally or topically, bismuth nitrate may cause mild skin irritation.”

    Bismuth Nitrate · Natural Medicines adverse-effect record, reported in cluster headache.

    5 sources cited
    1. 100540. - Jaeger A, Kopferschmitt J, Sauder Ph, Flesch F, Tournoud C. Diagnosis in clinical toxicology. In: Bolt HM, de Wolff FA, Henderson PT (eds) Medical Toxicology. Archives of Toxicology (Supplement). Berlin/Heidelberg, Germany: Springer-Verlag; 1992:29-39. PubMed
    2. 100547. Bismuth nitrate; MSDS No. B3396 [Online]; Mallenckrodt Baker: Phillipsburg, NJ, December 8, 1996. https://hazard.com/msds/mf/baker/baker/files/b3396.htm (accessed December 27, 2019).
    3. 100550. Von Bose MJ, Zaudig M. Encephalopathy resembling Creutzfeldt-Jakob disease following oral, prescribed doses of bismuth nitrate. Br J Psychiatry. 1991;158:278-80. PubMed
    4. 101507. Lewis RJ Sr. Hazardous Chemicals Desk Reference. 6th Edition. Hoboken, NJ: Wiley; 2008.
    5. 101508. Raafat BM, Samir WA, Khader MH. Met-Hemoglobin concentration reduction and methemoglobin reductase enhancement after applying of alpha-tocopherol and selenium combination as a radio protector against ionizing radiation exposure. Wulfenia J. 2012;19(10):37

    Cephalexin

    Listed in the ADVERSE REACTIONS section of the FDA label for Cephalexin. Read the label on DailyMed ›

  • Anxiety or restlessness / Fever / Nausea Additional detail

    Bismuth Nitrate

    Recorded for Bismuth Nitrate in the same Natural Medicines adverse-effect record shown under Confusion above.

    Cephalexin

    Listed in the ADVERSE REACTIONS section of the FDA label for Cephalexin. Read the label on DailyMed ›

  • Tiredness / Dizziness Additional detail

    Bismuth Nitrate

    Recorded for Bismuth Nitrate in the same Natural Medicines adverse-effect record shown under Confusion above.

    Cephalexin

    Listed in the ADVERSE REACTIONS section of the FDA label for Cephalexin. Read the label on DailyMed ›

  • Headache Additional detail

    Bismuth Nitrate

    Recorded for Bismuth Nitrate in the same Natural Medicines adverse-effect record shown under Kidney problems above.

    Cephalexin

    Listed in the ADVERSE REACTIONS section of the FDA label for Cephalexin. Read the label on DailyMed ›

Reported for Bismuth Nitrate but not commonly for Cephalexin: trouble concentrating, shortness of breath, reduced appetite and low mood.

Effects for Cephalexin come from the ADVERSE REACTIONS section of its FDA label; effects for Bismuth Nitrate come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

From our Q&A

Questions About Bismuth Nitrate or Cephalexin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Bismuth Nitrate or Cephalexin, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Cephalexin

This page covers Bismuth Nitrate only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Cephalexin page lists 61 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Siberian Cocklebur (major), African Wild Potato (moderate) and Aristolochia (moderate).

By severity: 3 major · 47 moderate · 11 minor.

From our pharmacist’s overview on the Cephalexin page

“Cephalexin (Keflex) is one of the most commonly prescribed oral antibiotics, usually for skin and urinary infections, and its supplement list warrants genuine care rather than a quick skim. Three of the 61 ingredients on file rate major.”

Reviewed by 2 · Jul 18, 2026

Open the Cephalexin interaction page

One more smart check

Taking Bismuth Nitrate as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1 real supplement products containing Bismuth Nitrate, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Bismuth Nitrate. Even though Bismuth Nitrate itself has no known interaction with Cephalexin, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Bismuth Nitrate and Cephalexin Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Bismuth Nitrate
Steady interest

#1,311 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Cephalexin
Top 5%

#139 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Bismuth Nitrate reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Bismuth Nitrate and Cephalexin records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Bismuth Nitrate

What is Bismuth Nitrate?

  • Upset stomach and indigestion
  • Diarrhea
  • Wound and skin protection (topical)
  • Mild antiseptic

Bismuth nitrate is a bismuth-based chemical compound that was historically used for stomach complaints and as a mild topical antiseptic, but it is not a common modern dietary supplement and is rarely used today. Better-studied bismuth products (like bismuth subsalicylate) have largely replaced it, and bismuth nitrate carries safety concerns, so talk with a pharmacist or doctor before using any bismuth product.

Not applicable (a chemical bismuth compound, not a plant) · Compounded powders, topical preparations, and historically in some oral antacid or stomach formulas

An interaction check asks whether these two react with each other — it does not ask whether Bismuth Nitrate is a good idea for someone in your situation. Here is what our Bismuth Nitrate record says about it on its own.

Bismuth Nitrate: dosing

There is no established standard dose of bismuth nitrate as a supplement, and it is not a typical over-the-counter product. Because of this, no specific safe amount can be recommended here.If a product containing bismuth nitrate is available to you, follow the directions on the label exactly and do not exceed them.

From our Bismuth Nitrate monograph — the full record covers uses, side effects and every documented interaction.

Read the full Bismuth Nitrate monograph & all interactions
Medication

About Cephalexin

What Is Cephalexin Used For?

Brand names: Keflex, Keftab, Cephalex, Lexin

Cephalexin treats bacterial infections caused by susceptible strains of bacteria. It is used for respiratory tract infections, ear infections (otitis media), skin and skin structure infections, bone infections, and genitourinary tract infections — including acute prostatitis.

It works only against bacterial infections — not viruses like colds or flu. Your prescriber should use it only when a bacterial infection is confirmed or strongly suspected, to help prevent antibiotic resistance.

Most-Reported Side Effects for Cephalexin

From FAERS, the FDA’s public side-effect reporting system (0 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Chronic kidney disease 2,157 reports
Renal failure 1,558 reports
Acute kidney injury 1,550 reports
Diarrhea 1,405 reports
Fatigue 1,303 reports
See full Cephalexin drug information
Keep checking

Other Drugs & Bismuth Nitrate

Browse every other medication we’ve checked against Bismuth Nitrate — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
0Moderate
0Minor
2,829No known interaction
No interaction 2,829 drugs checked — show the list
Evidence & sources

Bismuth Nitrate References

The 6 references that drive our Bismuth Nitrate monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. - Jaeger A, Kopferschmitt J, Sauder Ph, Flesch F, Tournoud C. Diagnosis in clinical toxicology. In: Bolt HM, de Wolff FA, Henderson PT (eds) Medical Toxicology. Archives of Toxicology (Supplement). Berlin/Heidelberg, Germany: Springer-Verlag; 1992:29-39. PubMed
  2. Bismuth nitrate; MSDS No. B3396 [Online]; Mallenckrodt Baker: Phillipsburg, NJ, December 8, 1996. https://hazard.com/msds/mf/baker/baker/files/b3396.htm (accessed December 27, 2019).
  3. Saberi-Firoozi M, Massarrat S, Zare S, et al. Effect of triple therapy or amoxycillin plus omeprazole or amoxycillin plus tinidazole plus omeprazole on duodenal ulcer healing, eradication of Helicobacter pylori, and prevention of ulcer relapse over a 1-ye
  4. Von Bose MJ, Zaudig M. Encephalopathy resembling Creutzfeldt-Jakob disease following oral, prescribed doses of bismuth nitrate. Br J Psychiatry. 1991;158:278-80. PubMed
  5. Lewis RJ Sr. Hazardous Chemicals Desk Reference. 6th Edition. Hoboken, NJ: Wiley; 2008.
  6. Raafat BM, Samir WA, Khader MH. Met-Hemoglobin concentration reduction and methemoglobin reductase enhancement after applying of alpha-tocopherol and selenium combination as a radio protector against ionizing radiation exposure. Wulfenia J. 2012;19(10):37

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Bismuth Nitrate and Cephalexin Together: Common Questions

Is it safe to take Bismuth Nitrate with Cephalexin?
We do not list a known interaction between Bismuth Nitrate and Cephalexin. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Bismuth Nitrate and Cephalexin have any of the same side effects?
Yes — our sources link each of them separately to 9 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Does Cephalexin interact with any supplements?
Yes. Cephalexin has documented interactions with 61 supplements in our database — Bismuth Nitrate is not one of them. The Cephalexin interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Cephalexin and Bismuth Nitrate?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.