Drug & supplement interaction

Guava + Penicillin V Potassium

Penicillin V Potassium brand names: V-Cillin K, Veetids, Pen VK, Beepen-VK, Ledercillin, and others.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Oct 4, 2026
The bottom line No known interaction

We found no known interaction between Guava and Penicillin V Potassium 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 Penicillin V Potassium

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 Penicillin V Potassium 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 Penicillin V Potassium and Guava? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Penicillin V Potassium

Interactions in our licensed database are recorded against drug classes, not just single drug names. Penicillin V Potassium is filed under 4 classifications — including antibiotic drugs, nephrotoxic drugs, seizure threshold lowering drugs. Guava has documented interactions with 1 drug class — the most serious being antidiabetes drugs (moderate) — and none of Penicillin V Potassium’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 — Penicillin V Potassium 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. Penicillin V Potassium)
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 Penicillin V Potassium 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.

  • A skin rash 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

    “Topically, guava leaf extract may cause contact dermatitis and worsen atopic dermatitis. Exacerbation of atopic dermatitis has been reported for a 17-year-old male who added tea bags containing guava leaf 30 grams to his bath to help treat his condition. His eczema worsened after bathing with the guava tea bags and improved after discontinuation of use.”

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

    1 source cited
    1. 95560. Obi M, Miyazaki Y, Yokozeki H, Nishioka K. Allergic contact dermatitis due to guava tea. Contact Dermatitis. 2001;44(2):116-7. PubMed

    Penicillin V Potassium

    Listed in the ADVERSE REACTIONS section of the FDA label for Penicillin V Potassium. Read the label on DailyMed ›

  • Nausea Additional detail

    Guava

    “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

    Penicillin V Potassium

    Listed in the ADVERSE REACTIONS section of the FDA label for Penicillin V Potassium. Read the label on DailyMed ›

Reported for Guava but not commonly for Penicillin V Potassium: stomach pain.

Effects for Penicillin V Potassium 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

Overlapping uses

What Penicillin V Potassium Is Prescribed For, and What Guava Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Penicillin V Potassium is a prescription medicine with approved uses on its FDA label. Guava is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Penicillin V Potassium is prescribed for: Penicillin V Potassium treats mild to moderately severe bacterial infections caused by penicillin-sensitive bacteria. These include streptococcal infections (such as strep throat and scarlet fever), pneumococcal respiratory infections, mild staphylococcal skin and soft-tissue infections, and fusospirochetosis (Vincent's gingivitis and pharyngitis — a mouth and throat infection). It is also used as a preventive (prophylactic) therapy: on an ongoing basis to prevent rheumatic fever and chorea from coming back, and — as suggested by the American Heart Association and American Dental Association — to help guard against bacterial endocarditis (infection of the heart valves) in certain patients with heart conditions undergoing dental or upper respiratory tract procedures. It should not be used this way in patients at particularly high risk, such as those with prosthetic heart valves.

Guava has been studied for:

  • Gingivitis studied, not established Guava has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Guava for gingivitis

    It is unclear if topical guava is beneficial in patients with gingivitis.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Penicillin V Potassium on your own; if you are taking Guava for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

Everything else you take

See Every Supplement That Interacts With Penicillin V Potassium

This page covers Guava only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Penicillin V Potassium page lists 56 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), Aristolochia (moderate) and Bacillus Coagulans (moderate).

Open the Penicillin V Potassium 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 Penicillin V Potassium, 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 Penicillin V Potassium 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 25%

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

29 days ago today
Medication Penicillin V Potassium
Steady interest

#1,842 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 October 4, 2026. The Guava and Penicillin V Potassium 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
Medication

About Penicillin V Potassium

What Is Penicillin V Potassium Used For?

Brand names: V-Cillin K, Veetids, Pen VK, Beepen-VK, Ledercillin, Pen-Vee K

Penicillin V Potassium treats mild to moderately severe bacterial infections caused by penicillin-sensitive bacteria. These include streptococcal infections (such as strep throat and scarlet fever), pneumococcal respiratory infections, mild staphylococcal skin and soft-tissue infections, and fusospirochetosis (Vincent's gingivitis and pharyngitis — a mouth and throat infection).

It is also used as a preventive (prophylactic) therapy: on an ongoing basis to prevent rheumatic fever and chorea from coming back, and — as suggested by the American Heart Association and American Dental Association — to help guard against bacterial endocarditis (infection of the heart valves) in certain patients with heart conditions undergoing dental or upper respiratory tract procedures. It should not be used this way in patients at particularly high risk, such as those with prosthetic heart valves.

See full Penicillin V Potassium drug information
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 Penicillin V Potassium, ranked by severity
Evidence & sources

Guava References

The 3 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. Obi M, Miyazaki Y, Yokozeki H, Nishioka K. Allergic contact dermatitis due to guava tea. Contact Dermatitis. 2001;44(2):116-7. PubMed
  2. 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
  3. 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 Penicillin V Potassium Together: Common Questions

Is it safe to take Guava with Penicillin V Potassium?
We do not list a known interaction between Guava and Penicillin V Potassium. 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 Penicillin V Potassium have any of the same side effects?
Yes — our sources link each of them separately to 2 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.
Are Guava and Penicillin V Potassium used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Guava in each. That is a conversation for your prescriber, especially if Penicillin V Potassium is being adjusted to a target.
How was the Guava and Penicillin V Potassium combination checked?
Interactions in our licensed database are recorded against drug classes. Penicillin V Potassium is filed under 4 classifications, and Guava has documented interactions with 1 drug class — none of Penicillin V Potassium'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 — Penicillin V Potassium 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 Penicillin V Potassium interact with any supplements?
Yes. Penicillin V Potassium has documented interactions with 56 supplements in our database — Guava is not one of them. The Penicillin V Potassium 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 Penicillin V Potassium drug information The full plain-English guide to this medication Penicillin V Potassium supplement interactions Every supplement checked against Penicillin V Potassium, 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 Penicillin V Potassium 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.