Drug & supplement interaction

Molybdenum + Valacyclovir

Valacyclovir brand name: Valtrex.

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 Molybdenum and Valacyclovir 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

Molybdenum and Valacyclovir

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 Valacyclovir and Molybdenum 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 Molybdenum at all — not against Valacyclovir, 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.

Molybdenum safety at a glance

Molybdenum overall Use caution Safe in amounts found in food, but high-dose supplements may cause problems and are rarely necessary.
Pregnancy Likely Safe When used orally and appropriately. Molybdenum crosses the placenta by passive diffusion and is exchanged freely between the mother and fetus. However, molybden... Read the full pregnancy detail
Breastfeeding Likely Safe When used orally and appropriately. Molybdenum is safe when used in amounts that do not exceed the Tolerable Upper Intake Level (UL) of 2 mg/day for breast-feed... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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

No Interaction Found — But Data Suggests Molybdenum and Valacyclovir 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.

  • Hallucinations / Seizures / Low mood Worth acting on Additional detail

    Molybdenum

    “In one case report of a man in his late thirties, dietary supplementation with molybdenum 300-800 micrograms daily for a cumulative dose of 13.5 mg over 18 days resulted in acute psychosis with visual and auditory hallucinations, petit mal seizures, and a life-threatening grand mal attack, related to frontal cortical damage. Chelation therapy with calcium ethylene diamine tetraacetic acid (CaEDTA) was required.”

    Molybdenum · Natural Medicines adverse-effect record, reported in depression.

    1 source cited
    1. 63368. Momcilovic, B. A case report of acute human molybdenum toxicity from a dietary molybdenum supplement--a new member of the "Lucor metallicum" family. Arh.Hig.Rada Toksikol. 1999;50(3):289-297. DOI

    Valacyclovir

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

Effects for Valacyclovir come from the ADVERSE REACTIONS section of its FDA label; effects for Molybdenum 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.

Special populations

Molybdenum in Pregnancy & Breastfeeding

Pregnancy Likely Safe

When used orally and appropriately. Molybdenum crosses the placenta by passive diffusion and is exchanged freely between the mother and fetus. However, molybdenum is safe when used in amounts that do not exceed the Tolerable Upper Intake Level (UL) of 1.7 mg/day for women 14 to 18 years, or 2 mg/day for women 19 years of age and older.

Pregnancy Possibly Unsafe

When used orally in high doses. Molybdenum might not be safe during pregnancy when used in doses exceeding the UL of 1.7 mg/day for women 14 to 18 years, or 2 mg/day for women 19 and older.

Lactation Likely Safe

When used orally and appropriately. Molybdenum is safe when used in amounts that do not exceed the Tolerable Upper Intake Level (UL) of 2 mg/day for breast-feeding women 19 years of age or older, or 1.7 mg/day for breast-feeding women ages 14 to 18 years.

Lactation Possibly Unsafe

When used orally in high doses. Molybdenum might not be safe when used in doses exceeding the UL of 2 mg/day for breast-feeding women 19 or older, or 1.7 mg/day for breast-feeding women ages 14 to 18 years.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

From our Q&A

Questions About Molybdenum or Valacyclovir

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

This page covers Molybdenum only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Valacyclovir page lists 27 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), African Wild Potato (moderate), Banderol (moderate), Biofeedback (moderate) and Caffeic Acid (moderate).

By severity: 1 major · 17 moderate · 9 minor.

From our pharmacist’s overview on the Valacyclovir page

“Valacyclovir (Valtrex) works against herpes outbreaks only if enough of it gets absorbed into your blood, and most of this list threatens exactly that. Of the 27 supplements on file, 17 can change how well oral medicines like this one are absorbed, and the single major-rated entry, activated charcoal, binds drugs in the gut outright.”

Reviewed by 2 · Jul 18, 2026

Open the Valacyclovir interaction page

One more smart check

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

We hold 10,352 real supplement products containing Molybdenum, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Molybdenum. Even though Molybdenum itself has no known interaction with Valacyclovir, 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 Molybdenum and Valacyclovir 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 Molybdenum
Top 5%

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

29 days ago today
Medication Valacyclovir
Top 5%

#31 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 Molybdenum reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Molybdenum and Valacyclovir records this page draws on were last updated July 11, 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 Molybdenum

What is Molybdenum?

  • Correcting molybdenum deficiency
  • Supporting enzyme function
  • General nutritional supplementation
  • Sulfite sensitivity (popular claim)

Molybdenum is an essential trace mineral your body needs in tiny amounts to help certain enzymes work. Most people get enough from a normal diet, so supplements are rarely needed unless a doctor identifies a true deficiency. At normal dietary amounts it is considered safe, but high-dose supplements should be used cautiously and under professional guidance.

Tablets, capsules, multivitamin/mineral products, liquid drops

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

Molybdenum: dosing

There is no special "treatment dose" of molybdenum for most people, because deficiency is rare and the body only needs a tiny amount. Health authorities have set recommended daily intakes that are met easily through a normal diet.If you choose to use a supplement, follow the dose on the product label and do not exceed it.

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

Read the full Molybdenum monograph & all interactions
Medication

About Valacyclovir

What Is Valacyclovir Used For?

Brand name: Valtrex

Valacyclovir tablets are used in adults to treat cold sores (herpes labialis), genital herpes (initial and recurrent episodes), and shingles (herpes zoster). They can also be taken daily as suppressive therapy to reduce how often genital herpes outbreaks occur, and to lower the risk of passing genital herpes to a partner.

In children and adolescents, valacyclovir tablets are used to treat cold sores in those aged 12 and older, and chickenpox in those aged 2 to under 18. Valacyclovir has not been established as safe and effective for most uses in immunocompromised patients, with the exception of suppressive therapy for genital herpes in HIV-infected adults.

Most-Reported Side Effects for Valacyclovir

From FAERS, the FDA’s public side-effect reporting system (70,056 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 4,317 reports
Nausea 3,985 reports
Diarrhea 3,648 reports
Headache 2,964 reports
Fever 2,753 reports
See full Valacyclovir drug information
Keep checking

Other Drugs & Molybdenum

Browse every other medication we’ve checked against Molybdenum — 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 Molybdenum 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 Molybdenum list.

See the full Molybdenum interactions page
See every supplement checked against Valacyclovir, ranked by severity
Evidence & sources

Molybdenum References

The 8 references that drive our Molybdenum 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. Chan S, Gerson B, Subramaniam S. The role of copper, molybdenum, selenium, and zinc in nutrition and health. Clin Lab Med 1998;18:673-85. DOI
  2. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press, 2002.
  3. Rajagopalan KV. Molybdenum: an essential trace element in human nutrition. Annu Rev Nutr 1988;8:401-27. PubMed
  4. Selden AI, Berg NP, Soderbergh A, Bergstrom BE. Occupational molybdenum exposure and a gouty electrician. Occup Med (Lond) 2005;55:145-8. PubMed
  5. Al-Saleh E, Nandakumaran M, Al-Shammari M, Al-Harouny A. Maternal-fetal status of copper, iron, molybdenum, selenium and zinc in patients with gestational diabetes. J Matern Fetal Neonatal Med 2004;16:15-21. PubMed
  6. Koster R, Vieluf D, Kiehn M, et al. Nickel and molybdenum contact allergies in patients with coronary in-stent restenosis. Lancet 2000;356:1895-7. PubMed
  7. Vyskocil A, Viau C. Assessment of molybdenum toxicity in humans. J Appl Toxicol 1999;19:185-92. DOI
  8. Momcilovic, B. A case report of acute human molybdenum toxicity from a dietary molybdenum supplement--a new member of the "Lucor metallicum" family. Arh.Hig.Rada Toksikol. 1999;50(3):289-297. DOI

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 Molybdenum and Valacyclovir Together: Common Questions

Is it safe to take Molybdenum with Valacyclovir?
We do not list a known interaction between Molybdenum and Valacyclovir. 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 Molybdenum and Valacyclovir have any of the same side effects?
Yes — our sources link each of them separately to 3 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 Valacyclovir interact with any supplements?
Yes. Valacyclovir has documented interactions with 27 supplements in our database — Molybdenum is not one of them. The Valacyclovir 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

Molybdenum monograph Uses, safety profile, and every drug interaction in one place Valacyclovir drug information The full plain-English guide to this medication Valacyclovir supplement interactions Every supplement checked against Valacyclovir, 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 8 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Valacyclovir and Molybdenum?

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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.