Drug & supplement interaction

Cannabinol (cbn) + Cephalexin

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

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Cannabinol (cbn) 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

Cannabinol (cbn) 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 Cannabinol (cbn) 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.

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.

Cannabinol (cbn) safety at a glance

Cannabinol (cbn) overall Use caution CBN is generally considered mild, but human safety data are limited and product quality varies.
Pregnancy Avoid Cannabis-derived compounds are not considered safe in pregnancy, so avoid CBN.
Breastfeeding Avoid Cannabinoids can pass into breast milk, so avoid CBN while breastfeeding.

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

Still wondering about combining Cephalexin and Cannabinol (cbn)? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Cephalexin

Interactions in our licensed database are recorded against drug classes, not just single drug names. Cephalexin is filed under 7 classifications — including organic anion transporter 3 (oat3) substrates, organic anion transporter 1 (oat1) substrates, antibiotic drugs. Cannabinol (cbn) has documented interactions with 5 drug classes — the most serious being cytochrome p450 2b6 (cyp2b6) substrates (moderate), cytochrome p450 2c9 (cyp2c9) inhibitors (moderate) and cytochrome p450 2c9 (cyp2c9) substrates (moderate) — and none of Cephalexin’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Cannabinol (cbn) Does Interact With Other Medications

Cannabinol (cbn) has 389 moderate known drug interactions in our database — Cephalexin isn’t one of them. If you take anything else, check it against the full list below.

Moderate 389 No known interaction 2,441 (incl. Cephalexin)
Taking anything else?

Check Another of Your Medications Against Cannabinol (cbn)

Covers the 2,830 medications we’ve checked against Cannabinol (cbn). Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Cannabinol (cbn) and Cephalexin May Share a Side Effect

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.

  • Headache Additional detail

    Cannabinol (cbn)

    “Orally, cannabinol may cause headache and somnolence.”

    Cannabinol (cbn) · Natural Medicines adverse-effect record, reported in cluster headache.

    1 source cited
    1. 113055. Bonn-Miller MO, Feldner MT, Bynion TM, Eglit GML, Brunstetter M, Kalaba M, Zvorsky I, Peters EN, Hennesy M. A double-blind, randomized, placebo-controlled study of the safety and effects of CBN with and without CBD on sleep quality. Exp Clin Psychopharmac PubMed

    Cephalexin

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

Reported for Cannabinol (cbn) but not commonly for Cephalexin: drowsiness.

Effects for Cephalexin come from the ADVERSE REACTIONS section of its FDA label; effects for Cannabinol (cbn) 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 Cannabinol (cbn) 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 Cannabinol (cbn) 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 Cannabinol (cbn) 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

How much people look this up

Where Cannabinol (cbn) 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 Cannabinol (cbn)
Top half

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

29 days ago today
Medication Cephalexin
Top 5%

#67 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 Cannabinol (cbn) reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Cannabinol (cbn) 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 Cannabinol (cbn)

What is Cannabinol (cbn)?

  • Sleep support
  • Relaxation
  • Pain or discomfort
  • Appetite-related concerns

Cannabinol (CBN) is a minor cannabinoid found in the cannabis plant, often marketed as a 'sleep' aid, but solid human research is very limited. Because it comes from cannabis and product quality varies widely, talk with your pharmacist or doctor before trying it, and avoid it during pregnancy and breastfeeding.

Cannabaceae · Aged cannabis flower and resin (where THC degrades into CBN) · Oils and tinctures, gummies, capsules, vape products, topicals

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

Cannabinol (cbn): dosing

There is no established, standardized dose for CBN. Research is too limited to recommend a specific milligram amount, and products vary widely in strength and quality.If you choose to try a CBN product, follow the directions on the label and start with the lowest amount.

From our Cannabinol (cbn) monograph — the full record covers uses, side effects and every documented interaction.

Read the full Cannabinol (cbn) 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 & Cannabinol (cbn)

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

0Major
389Moderate
0Minor
2,440No known interaction
389 Moderate 2,440 No interaction
Moderate

389 interactions

Showing 60 of 389 moderate interactions — see all 389 on the Cannabinol (cbn) page.

No interaction 2,440 drugs checked — show the list

We also checked Cannabinol (cbn) against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,440 medications checked with no known interaction — see the full Cannabinol (cbn) list.

See the full Cannabinol (cbn) interactions page
See every supplement checked against Cephalexin, ranked by severity
Evidence & sources

Cannabinol (cbn) References

The 3 references that drive our Cannabinol (cbn) 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. Watanabe K, Yamaori S, Funahashi T, Kimura T, Yamamoto I. Cytochrome P450 enzymes involved in the metabolism of tetrahydrocannabinols and cannabinol by human hepatic microsomes. Life Sci. 2007;80(15):1415-9. PubMed
  2. Nasrin S, Watson CJW, Perez-Paramo YX, Lazarus P. Cannabinoid Metabolites as Inhibitors of Major Hepatic CYP450 Enzymes, with Implications for Cannabis-Drug Interactions. Drug Metab Dispos 2021;49(12):1070-1080. PubMed
  3. Bonn-Miller MO, Feldner MT, Bynion TM, Eglit GML, Brunstetter M, Kalaba M, Zvorsky I, Peters EN, Hennesy M. A double-blind, randomized, placebo-controlled study of the safety and effects of CBN with and without CBD on sleep quality. Exp Clin Psychopharmac PubMed

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 Cannabinol (cbn) and Cephalexin Together: Common Questions

Is it safe to take Cannabinol (cbn) with Cephalexin?
We do not list a known interaction between Cannabinol (cbn) 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 Cannabinol (cbn) and Cephalexin have any of the same side effects?
Yes — our sources link each of them separately to one 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.
How was the Cannabinol (cbn) and Cephalexin combination checked?
Interactions in our licensed database are recorded against drug classes. Cephalexin is filed under 7 classifications, and Cannabinol (cbn) has documented interactions with 5 drug classes — none of Cephalexin's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Cannabinol (cbn) interact with any other medications?
Yes. Cannabinol (cbn) has 389 documented drug interactions in our database — Cephalexin is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Cephalexin interact with any supplements?
Yes. Cephalexin has documented interactions with 61 supplements in our database — Cannabinol (cbn) 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

Where next

Keep Exploring

Cannabinol (cbn) monograph Uses, safety profile, and every drug interaction in one place Cephalexin drug information The full plain-English guide to this medication Cephalexin supplement interactions Every supplement checked against Cephalexin, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 3 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Cephalexin and Cannabinol (cbn)?

Our pharmacists answer your medication & supplement questions — free.

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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.