Drug & supplement interaction

Vitamin O + Phendimetrazine

Phendimetrazine brand names: Plegine, Metra, Weightrol.

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

We found no known interaction between Vitamin O and Phendimetrazine 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.

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Interaction report

Vitamin O and Phendimetrazine

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 Phendimetrazine and Vitamin O 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 Vitamin O at all — not against Phendimetrazine, 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.

Vitamin O safety at a glance

Vitamin O overall Use caution Products sold as 'Vitamin O' have unproven claims and their ingredients vary, so quality and safety are uncertain.
Pregnancy Avoid There is no safety data, so avoid during pregnancy.
Breastfeeding Avoid There is no safety data, so avoid while breastfeeding.

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

Still wondering about combining Phendimetrazine and Vitamin O? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

What Phendimetrazine’s Own FDA Label Lists

This is not an interaction — none of it involves Vitamin O. These are the most notable effects listed in the ADVERSE REACTIONS section of Phendimetrazine’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 2 of them are worth acting on rather than waiting out — marked below.

  • Pain or burning when passing urine Worth acting on
  • Raised blood pressure Worth acting on
  • Tremor or shakiness
  • Flushing
  • Sweating
  • A fast or pounding heartbeat
  • Anxiety or restlessness
  • Trouble sleeping
  • Constipation
  • Stomach pain

Showing the 10 most notable of 14 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Phendimetrazine. Read the label on DailyMed › Vitamin O’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Vitamin O side to compare — that is a limit of the record, not a statement that Vitamin O has no side effects.

Everything else you take

See Every Supplement That Interacts With Phendimetrazine

This page covers Vitamin O only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phendimetrazine page lists 17 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).

By severity: 1 major · 7 moderate · 9 minor.

From our pharmacist’s overview on the Phendimetrazine page

“Of the 17 supplements on file for phendimetrazine, an appetite-suppressant stimulant prescribed short term for weight loss, activated charcoal is the one that demands real caution. Charcoal binds medications in the gut and can sharply cut how much of a drug your body absorbs, leaving you with less appetite control than your prescriptio…”

Reviewed by 2 · Jul 18, 2026

Open the Phendimetrazine interaction page

How much people look this up

Where Vitamin O and Phendimetrazine 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 Vitamin O
Steady interest

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

29 days ago today
Medication Phendimetrazine
Top 10%

#181 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. Vitamin O is not yet covered by that licensed database, so its write-up cites publicly available medical sources directly (see the references below).
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Vitamin O reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Vitamin O and Phendimetrazine records this page draws on were last updated June 22, 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 Vitamin O

What is Vitamin O?

  • Claimed to add 'stabilized oxygen' to the body
  • General energy and wellness
  • Marketed for improved breathing or vitality

"Vitamin O" is not a real vitamin. It is a marketing name used for liquid products typically containing saltwater (a saline solution) sold with claims of providing 'stabilized oxygen' to the body. There is no credible scientific evidence that these products work, and U.S. regulators have taken action against false advertising for them, so they are best avoided.

Not applicable (manufactured liquid product) · Liquid drops

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

Vitamin O: dosing

There is no established or recommended dose for Vitamin O because it is not a recognized nutrient and has no proven benefit. Different brands give different directions, usually a set number of drops in water.Since the product is unproven, the most cautious advice is to avoid it.

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

Read the full Vitamin O monograph & all interactions
Medication

About Phendimetrazine

What Is Phendimetrazine Used For?

Brand names: Plegine, Metra, Weightrol

Phendimetrazine tartrate is used to help manage exogenous obesity (excess body weight from outside causes like diet and lifestyle) as a short-term addition to a calorie-restricted diet. It is intended for adults with a BMI of 30 or higher, or a BMI of 27 or higher when other risk factors — such as high blood pressure, diabetes, or high cholesterol — are also present.

It is approved for use as monotherapy only, meaning it must not be combined with other weight-loss drugs or stimulants. Both the tablet form and the extended-release capsule form are approved for this purpose. This medication is meant to be used for only a few weeks as part of a broader weight-management plan.

See full Phendimetrazine drug information
Keep checking

Other Drugs & Vitamin O

Browse every other medication we’ve checked against Vitamin O — 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
2,829 No interaction
No interaction 2,829 drugs checked — show the list

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

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Vitamin O list.

See the full Vitamin O interactions page
See every supplement checked against Phendimetrazine, ranked by severity
Evidence & sources

Vitamin O References

The 2 sources that drive our Vitamin O monograph — publicly available pages from reputable medical and government organizations. Every link was verified to work before publishing. Vitamin O is not covered by the licensed Natural Medicines interaction database, so its page cites these public sources directly.

  1. Dietary Supplements: What You Need to Know — NIH Office of Dietary Supplements Source
  2. Dietary and Herbal Supplements — NIH National Center for Complementary and Integrative Health Source

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 Vitamin O and Phendimetrazine Together: Common Questions

Is it safe to take Vitamin O with Phendimetrazine?
We do not list a known interaction between Vitamin O and Phendimetrazine. 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.
Does Phendimetrazine interact with any supplements?
Yes. Phendimetrazine has documented interactions with 17 supplements in our database — Vitamin O is not one of them. The Phendimetrazine 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

Vitamin O monograph Uses, safety profile, and every drug interaction in one place Phendimetrazine drug information The full plain-English guide to this medication Phendimetrazine supplement interactions Every supplement checked against Phendimetrazine, 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 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Phendimetrazine and Vitamin O?

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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.