Drug & supplement interaction

Guava + Methylene Blue

Methylene Blue brand names: Urolene Blue, Provayblue.

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 Guava and Methylene Blue 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

Guava and Methylene Blue

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 Methylene Blue and Guava 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.

Guava safety at a glance

Guava overall Use caution Guava fruit is generally safe as a food, but leaf extracts and supplements are less studied.
Pregnancy Use caution Guava fruit as a food is fine, but concentrated leaf supplements are not well studied and are best avoided.
Breastfeeding Likely Safe When guava fruit is consumed as food. There is insufficient reliable information available about the safety of guava fruit or leaf when used for medicinal purpo... 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 Methylene Blue and Guava? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Methylene Blue

Interactions in our licensed database are recorded against drug classes, not just single drug names. Methylene Blue is filed under 3 classifications — serotonergic drugs, serotonergic drugs, oral drugs. Guava has documented interactions with 1 drug class — the most serious being antidiabetes drugs (moderate) — and none of Methylene Blue’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

Guava Does Interact With Other Medications

Guava has 86 moderate known drug interactions in our database — Methylene Blue isn’t one of them. If you take anything else, check it against the full list below.

Moderate 86 No known interaction 2,744 (incl. Methylene Blue)
Taking anything else?

Check Another of Your Medications Against Guava

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

What to actually watch for

No Interaction Found — But Data Suggests Guava and Methylene Blue 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.

  • Nausea Additional detail

    Guava

    “Orally, guava leaf extract may cause transient abdominal pain or nausea. Topically, guava leaf extract may cause contact dermatitis.”

    Guava · Natural Medicines adverse-effect record, reported in dermatitis.

    2 sources cited
    1. 101782. Doubova SV, Morales HR, Hernández SF, et al. Effect of a Psidii guajavae folium extract in the treatment of primary dysmenorrhea: a randomized clinical trial. J Ethnopharmacol. 2007;110(2):305-10. PubMed
    2. 95560. Obi M, Miyazaki Y, Yokozeki H, Nishioka K. Allergic contact dermatitis due to guava tea. Contact Dermatitis. 2001;44(2):116-7. PubMed

    “Orally, transient abdominal pain or nausea has been reported in a clinical trial.”

    Guava · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    1 source cited
    1. 101782. Doubova SV, Morales HR, Hernández SF, et al. Effect of a Psidii guajavae folium extract in the treatment of primary dysmenorrhea: a randomized clinical trial. J Ethnopharmacol. 2007;110(2):305-10. PubMed

    Methylene Blue

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

Reported for Guava but not commonly for Methylene Blue: stomach pain and a skin rash.

Effects for Methylene Blue come from the ADVERSE REACTIONS section of its FDA label; effects for Guava 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

Guava in Pregnancy & Breastfeeding

Lactation Likely Safe

When guava fruit is consumed as food. There is insufficient reliable information available about the safety of guava fruit or leaf when used for medicinal purposes during pregnancy and lactation.

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

Everything else you take

See Every Supplement That Interacts With Methylene Blue

This page covers Guava only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Methylene Blue page lists 38 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Lithium (major), 5-htp (moderate), Acetyl-l-carnitine (moderate) and Ayahuasca (moderate).

By severity: 2 major · 25 moderate · 11 minor.

From our pharmacist’s overview on the Methylene Blue page

“The pairing I would worry about first with methylene blue (Urolene Blue, Provayblue) is anything that raises serotonin, and lithium heads that group with a major rating. Methylene blue inhibits monoamine oxidase A, the enzyme that breaks serotonin down, so combining it with serotonin-boosting supplements can tip someone into serotonin…”

Reviewed by 2 · Jul 18, 2026

Open the Methylene Blue interaction page

One more smart check

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

We hold 484 real supplement products containing Guava, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Guava. Even though Guava itself has no known interaction with Methylene Blue, 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 Guava and Methylene Blue 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 Guava
Top half

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

29 days ago today
Medication Methylene Blue
Top 5%

#53 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 Guava reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Guava and Methylene Blue 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 Guava

What is Guava?

  • Diarrhea and digestive upset
  • Blood sugar support
  • Cholesterol support
  • Wound and skin care
  • Cough and sore throat

Guava is a tropical fruit tree whose leaves and fruit have a long history of folk use for diarrhea, blood sugar, and general wellness. The fruit is a nutritious food rich in vitamin C, but evidence for guava leaf supplements treating specific health conditions is limited and mostly early. If you want to try guava leaf products, talk with your pharmacist or doctor first, especially if you take medicines or have a health condition.

Psidium guajava · Myrtaceae · Leaves, fruit, and bark · Tea, capsules, leaf extract, fresh fruit, juice, powder

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

Guava: dosing

There is no official, standardized dose for guava leaf supplements. The amount in products varies widely depending on the form (tea, capsule, or extract) and how concentrated it is.The best approach is to follow the directions on the product label and not exceed the recommended amount. Because quality and strength differ between brands, choose products from reputable companies.

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

Read the full Guava monograph & all interactions
Keep checking

Other Drugs & Guava

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

0Major
86Moderate
0Minor
2,743No known interaction
86 Moderate 2,743 No interaction
Moderate

86 interactions

Showing 60 of 86 moderate interactions — see all 86 on the Guava page.

No interaction 2,743 drugs checked — show the list

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

Showing the 60 most looked-up of 2,743 medications checked with no known interaction — see the full Guava list.

See the full Guava interactions page
See every supplement checked against Methylene Blue, ranked by severity
Evidence & sources

Guava References

The 7 references that drive our Guava 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. Lozoya, X., Reyes-Morales, H., Chavez-Soto, M. A., Martinez-Garcia, Mdel C., Soto-Gonzalez, Y., and Doubova, S. V. Intestinal anti-spasmodic effect of a phytodrug of Psidium guajava folia in the treatment of acute diarrheic disease. J Ethnopharmacol 2002 PubMed
  2. Obi M, Miyazaki Y, Yokozeki H, Nishioka K. Allergic contact dermatitis due to guava tea. Contact Dermatitis. 2001;44(2):116-7. PubMed
  3. Singh RB, Rastogi SS, Singh R, Ghosh S, Niaz MA. Effects of guava intake on serum total and high-density lipoprotein cholesterol levels and on systemic blood pressure. Am J Cardiol. 1992;70(15):1287-91. PubMed
  4. Nayak N, Varghese J, Shetty S, et al. Evaluation of a mouthrinse containing guava leaf extract as part of comprehensive oral care regimen- a randomized placebo-controlled clinical trial. BMC Complement Altern Med. 2019;19(1):327. PubMed
  5. Kakuo S, Fushimi T, Kawasaki K, Nakamura J, Ota N. Effects of Psidium guajava Linn. Leaf extract in Japanese subjects with knee pain: a randomized, double-blind, placebo-controlled, parallel pilot study. Aging Clin Exp Res. 2018;30(11):1391-1398. PubMed
  6. Gutiérrez RM, Mitchell S, Solis RV. Psidium guajava: a review of its traditional uses, phytochemistry and pharmacology. J Ethnopharmacol. 2008;117(1):1-27. PubMed
  7. Doubova SV, Morales HR, Hernández SF, et al. Effect of a Psidii guajavae folium extract in the treatment of primary dysmenorrhea: a randomized clinical trial. J Ethnopharmacol. 2007;110(2):305-10. 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 Guava and Methylene Blue Together: Common Questions

Is it safe to take Guava with Methylene Blue?
We do not list a known interaction between Guava and Methylene Blue. 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 Guava and Methylene Blue 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 Guava and Methylene Blue combination checked?
Interactions in our licensed database are recorded against drug classes. Methylene Blue is filed under 3 classifications, and Guava has documented interactions with 1 drug class — none of Methylene Blue'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 Guava interact with any other medications?
Yes. Guava has 86 documented drug interactions in our database — Methylene Blue 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 Methylene Blue interact with any supplements?
Yes. Methylene Blue has documented interactions with 38 supplements in our database — Guava is not one of them. The Methylene Blue 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

Guava monograph Uses, safety profile, and every drug interaction in one place Methylene Blue supplement interactions Every supplement checked against Methylene Blue, 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 7 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Methylene Blue and Guava?

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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.