Drug & supplement interaction

Procaine + Chlorzoxazone

Chlorzoxazone brand names: Parafon Forte DSC, Paraflex.

Major Interaction
Medically reviewed by · Updated September 2026
The bottom line Major

Procaine has a major interaction with Chlorzoxazone. Intravenous use of procaine hydrochloride is contraindicated.

Read the full interaction report
SeverityMajor
LikelihoodProbable
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Procaine and Chlorzoxazone

Here is the interaction we found between these two, with the evidence behind it.

Major

SKELETAL MUSCLE RELAXANTS

Why this applies to Chlorzoxazone

Chlorzoxazone falls under SKELETAL MUSCLE RELAXANTS — the group Procaine interacts with.

Intravenous use of procaine hydrochloride is contraindicated.
Severity Major Likelihood Probable Evidence D

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist of this one. Chlorzoxazone is a muscle relaxant, and pairing it with procaine (the anesthetic in some 'anti-aging' products) raises a caution flag. The concern listed is mainly about intravenous procaine, where the worry is that the two together could add up and depress your nervous system. In practice, that might look like extra drowsiness, dizziness, lightheadedness, or feeling unsteady on your feet.

I want to be honest about the strength of this: it's rated as theoretical, based on how these drugs work rather than hard patient studies. So please don't panic. But because the warning is serious in nature, I'd run any procaine-containing product past your pharmacist or doctor before mixing it with chlorzoxazone.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Procaine Also Interacts With Other Medications

Procaine has 36 major, 19 moderate known drug interactions in our database — the Chlorzoxazone one above is one of them. If you take anything else, check it against the full list below.

Major 36 Moderate 19 No known interaction 2,775 (incl. Chlorzoxazone)
Taking anything else?

Check Another of Your Medications Against Procaine

Covers the 2,830 medications we’ve checked against Procaine. Pick one to open its full report.

From our Q&A

Questions About Procaine or Chlorzoxazone

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Procaine or Chlorzoxazone, 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 Chlorzoxazone

This page covers Procaine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Chlorzoxazone page lists 26 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), Diosmin (moderate), European Mandrake (moderate) and Evodia (moderate).

By severity: 2 major · 15 moderate · 9 minor.

From our pharmacist’s overview on the Chlorzoxazone page

“Chlorzoxazone (Parafon Forte DSC, Paraflex) is a muscle relaxant for painful spasms, and its supplement list is one I want readers genuinely careful with. Twenty-six ingredients are on file, two rated major, led by activated charcoal, which can soak up the drug in the gut and cut what your body actually receives.”

Reviewed by 2 · Jul 18, 2026

Open the Chlorzoxazone interaction page

One more smart check

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

We hold 2 real supplement products containing Procaine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Procaine. Your product may carry other ingredients that interact with Chlorzoxazone too, on top of Procaine — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Procaine and Chlorzoxazone 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 Procaine
Top half

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

29 days ago today
Medication Chlorzoxazone
Top half

#1,094 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.

Supplement

About Procaine

What is Procaine?

  • Local anesthesia (medical/dental use)
  • Marketed 'anti-aging' supplements
  • General well-being and vitality claims
  • Mood and energy support (unproven)

Procaine is a synthetic local anesthetic (best known by the brand name Novocaine) used by doctors and dentists to numb tissue. It is not a true dietary supplement or herb, and the 'anti-aging' products built around it (such as GH3 or 'Gerovital') have weak evidence and real safety concerns. Talk to your pharmacist or doctor before using any product containing procaine.

Read the full Procaine monograph & all interactions
Medication

About Chlorzoxazone

What Is Chlorzoxazone Used For?

Brand names: Parafon Forte DSC, Paraflex

Chlorzoxazone tablets are used to relieve discomfort caused by acute, painful musculoskeletal conditions — things like muscle spasms and the pain that comes with them. It is meant to be used alongside rest, physical therapy, and other treatments, not as a stand-alone cure.

It is not intended for long-term muscle problems; it's most useful during a short-term flare of muscle pain and stiffness.

See full Chlorzoxazone drug information
Keep checking

Other Drugs & Procaine

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

36Major
19Moderate
0Minor
2,774No known interaction
36 Major 19 Moderate 2,774 No interaction
Major

36 interactions

Moderate

19 interactions

No interaction 2,774 drugs checked — show the list

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

Showing the 60 most looked-up of 2,774 medications checked with no known interaction — see the full Procaine list.

See the full Procaine interactions page
See every supplement checked against Chlorzoxazone, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Procaine monograph › Uses, safety, and every drug interaction in one place Chlorzoxazone supplement interactions › Every supplement checked against Chlorzoxazone, ranked by severity Chlorzoxazone drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Procaine and Chlorzoxazone Together: Common Questions

Can you take Procaine with Chlorzoxazone?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Procaine and Chlorzoxazone interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

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

Still Have a Question About Chlorzoxazone and Procaine?

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.