Drug & supplement interaction

Passion Flower + Doxycycline

Doxycycline brand names: Vibra-Tabs, Vibramycin, Doryx, Monodox, Doxycin, and others.

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 Passion Flower and Doxycycline 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 label for Doxycycline states a food rule worth keeping to, and 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

Passion Flower and Doxycycline

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 Doxycycline and Passion Flower 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.

Passion Flower safety at a glance

Passion Flower overall Use caution Generally well tolerated short-term, but it can cause drowsiness.
Pregnancy Possibly Unsafe When used orally. Some case reports suggest that passion flower use during the first and second trimesters of pregnancy may be associated with an increased risk... Read the full pregnancy detail
Breastfeeding Avoid Not enough safety information, so it is best avoided while breastfeeding.

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.

Pharmacist analysis

Passionflower is not known to have many clinically significant drug interactions.

Nevertheless, it has been shown to have sedative effects, which can be additive when used in conjunction with sedative medications (e.g., Benadryl, benzodiazepines, opioids, etc...).

Therefore, we do list interactions between Passionflower and CNS (central nervous system) depressants or other drugs with strong sedative effects.

Additionally, certain constituents of Passionflower (such as apigenin and vitexin) may inhibit certain drug transports, specifically OATP2B1 and OATP1A2.

These are responsible for the uptake of certain drugs and other compounds into the body.

As Passionflower can inhibit these transports, it is possible that it might reduce the bioavailability of drugs that are substrates for these transporters but studies are far from conclusive on the matter.

There is no known drug interaction between Passionflower and the drug in question here, however.

As always, be sure to speak with your doctor before making any changes to your medication regimen.

—

Still wondering about combining Doxycycline and Passion Flower? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Doxycycline

Interactions in our licensed database are recorded against drug classes, not just single drug names. Doxycycline is filed under 9 classifications — including tetracycline antibiotics, antibiotic drugs, p-glycoprotein substrates. Passion Flower has documented interactions with 3 drug classes — the most serious being cns depressants (moderate), cytochrome p450 3a4 (cyp3a4) substrates (minor) and organic anion-transporting polypeptide substrates (oatp) (minor) — and none of Doxycycline’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

Passion Flower Does Interact With Other Medications

Passion Flower has 248 moderate, 588 minor known drug interactions in our database — Doxycycline isn’t one of them. If you take anything else, check it against the full list below.

Moderate 248 Minor 588 No known interaction 1,994 (incl. Doxycycline)
Taking anything else?

Check Another of Your Medications Against Passion Flower

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

What to actually watch for

No Interaction Found — But Data Suggests Passion Flower and Doxycycline 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. 2 of them are worth acting on rather than waiting out — marked below.

  • Hives Worth acting on Additional detail

    Passion Flower

    “An idiosyncratic hypersensitivity reaction characterized by urticaria and cutaneous vasculitis has been reported in a 77-year-old male with rheumatoid arthritis after taking a specific combination product that included passion flower extract (Naturest).”

    Passion Flower · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).

    2 sources cited
    1. 68308. Smith, G. W., Chalmers, T. M., and Nuki, G. Vasculitis associated with herbal preparation containing Passiflora extract. Br J Rheumatol. 1993;32(1):87-88.
    2. 95038. Dantas LP, de Oliveira-Ribeiro A, de Almeida-Souza LM, Groppo FC. Effects of passiflora incarnata and midazolam for control of anxiety in patients undergoing dental extraction. Med Oral Patol Oral Cir Bucal. 2017;22(1):e95-e101. PubMed

    Doxycycline

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

  • An allergic reaction Worth acting on Additional detail

    Passion Flower

    “Orally, passion flower is well tolerated.

    Most Common Adverse Effects:

    Orally: Confusion, dizziness, hypersensitivity, and sedation.”

    Passion Flower · Natural Medicines adverse-effect record, reported in vertigo.

    Doxycycline

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

  • Vomiting / Nausea Additional detail

    Passion Flower

    “There is a case report involving a 34-year-old female who was hospitalized with severe nausea, vomiting, drowsiness, prolonged QT interval, and episodes of nonsustained ventricular tachycardia following use of passion flower extract tablets (Sedacalm, Bioplus Healthcare), 1500 mg on day 1 and 2000 mg on day 2 to relieve stress. All symptoms resolved within one week after passion flower was discontinued.”

    Passion Flower · Natural Medicines adverse-effect record, reported in myasthenia gravis.

    1 source cited
    1. 6251. Fisher AA, Purcell P, Le Couteur DG. Toxicity of Passiflora incarnata L. J Toxicol Clin Toxicol 2000;38:63-6.

    Doxycycline

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

Reported for Passion Flower but not commonly for Doxycycline: an irregular heartbeat, a fast or pounding heartbeat, drowsiness and dizziness.

Effects for Doxycycline come from the ADVERSE REACTIONS section of its FDA label; effects for Passion Flower 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

Passion Flower in Pregnancy & Breastfeeding

Pregnancy Possibly Unsafe

When used orally. Some case reports suggest that passion flower use during the first and second trimesters of pregnancy may be associated with an increased risk for premature rupture of membranes and meconium aspiration syndrome; however, causality has not been confirmed. The alkaloids harman and harmaline, which are sometimes found in passion flower, have been reported to have uterine stimulant activity. It is not known whether these constituents are present in sufficient quantities to have an effect.

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

How to take them

Some Doxycycline Products Have a Food Rule — Passion Flower Should Not Break It

At least one FDA label for a product containing Doxycycline says to take it on an empty stomach. Most supplements — Passion Flower included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Doxycycline on its own and move Passion Flower to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Doxycycline products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

2 DOSAGE AND ADMINISTRATION Take one Doxycycline capsule (40 mg) once daily in the morning on an empty stomach, preferably at least one hour prior to or two hours after meals.

From the Dosage and Administration section of the FDA label we read for Doxycycline — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

From our Q&A

Questions About Passion Flower or Doxycycline

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

This page covers Passion Flower only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Doxycycline page lists 166 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Oleander (major) and Siberian Cocklebur (major).

By severity: 7 major · 139 moderate · 20 minor.

From our pharmacist’s overview on the Doxycycline page

“St. John's wort is the supplement I would flag first for anyone on doxycycline (Vibramycin, Doryx), because it can speed the antibiotic out of the body and leave an infection undertreated.”

Reviewed by 2 · Jul 18, 2026

Open the Doxycycline interaction page

One more smart check

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

We hold 2,129 real supplement products containing Passion Flower, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Passion Flower. Even though Passion Flower itself has no known interaction with Doxycycline, 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 Passion Flower and Doxycycline 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 Passion Flower
Top 10%

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

29 days ago today
Medication Doxycycline
Top 5%

#41 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 Passion Flower reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Passion Flower and Doxycycline 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 Passion Flower

What is Passion Flower?

Passion Flower
  • Anxiety and stress
  • Trouble sleeping
  • Restlessness
  • Mild nervous tension
  • Muscle tension

Passion flower is a traditional calming herb that many people use for anxiety and sleep. Early studies hint it may help with mild anxiety and restlessness, but the evidence is limited and more research is needed. It is generally well tolerated short-term, but should be avoided in pregnancy and discussed with your pharmacist or doctor first.

Passiflora incarnata · Passifloraceae · Above-ground parts (flowers, leaves, stems) · Tea, capsules, tablets, liquid extracts, tinctures

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

Passion Flower: dosing

There is no single official or proven dose for passion flower. The amount in products varies widely depending on the form (tea, capsule, tincture, or extract) and how it is prepared. Many supplements are standardized to contain a certain percentage of the flavonoid vitexin.The safest approach is to follow the directions on the product label and not exceed them.

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

Read the full Passion Flower monograph & all interactions
Medication

About Doxycycline

What Is Doxycycline Used For?

Brand names: Vibra-Tabs, Vibramycin, Doryx, Monodox, Doxycin, Doxy, Doxylin, Doxy-D, Periostat, Doxycycline Injection, Oracea, Xyrosa

Doxycycline belongs to the tetracycline family of antibiotics. It's prescribed for many types of bacterial infections, including respiratory tract infections, sexually transmitted infections (STIs), tick-borne illnesses like Rocky Mountain spotted fever, and eye infections. It's also used to help prevent malaria and, in some cases, as a helper treatment for severe acne.

In situations where penicillin-type antibiotics can't be used — due to allergy, for example — doxycycline can step in as an alternative. It should only be used for infections that are proven or strongly suspected to be caused by bacteria.

See full Doxycycline drug information
Keep checking

Other Drugs & Passion Flower

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

0Major
248Moderate
588Minor
1,993No known interaction
248 Moderate 588 Minor 1,993 No interaction
Moderate

248 interactions

Showing 60 of 248 moderate interactions — see all 248 on the Passion Flower page.

Minor

588 interactions

Showing 60 of 588 minor interactions — see all 588 on the Passion Flower page.

No interaction 1,993 drugs checked — show the list

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

Showing the 60 most looked-up of 1,993 medications checked with no known interaction — see the full Passion Flower list.

See the full Passion Flower interactions page
See every supplement checked against Doxycycline, ranked by severity
Evidence & sources

Passion Flower References

The 19 references that drive our Passion Flower 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. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  3. Fisher AA, Purcell P, Le Couteur DG. Toxicity of Passiflora incarnata L. J Toxicol Clin Toxicol 2000;38:63-6.
  4. Akhondzadeh S, Naghavi HR, Shayeganpour A, et al. Passionflower in the treatment of generalized anxiety: a pilot double-blind randomized controlled trial with oxazepam. J Clin Pharm Ther 2001;26:363-7. PubMed
  5. Farnsworth N, Bingel A, Cordell G, et al. Potential value of plants as sources of new antifertility agents I. J Pharm Sci 1975;64:535-98. DOI
  6. Mori A, Hasegawa K, Murasaki M, et al. Clinical evaluation of Passiflamin (passiflora extract) on neurosis - multicenter double blind study in comparison with mexazolam. Rinsho Hyoka (Clinical Evaluation) 1993;21:383-440.
  7. Miyasaka LS, Atallah AN, Soares BG. Passiflora for anxiety disorder. Cochrane Database Syst Rev 2007;(1):CD004518. DOI
  8. Speroni E., Minghetti A. Neuropharmacological activity of extracts from Passiflora incarnata. Planta Med. 1988;54:488-91.
  9. Capasso A., Sorrentino L. Pharmacological studies on the sedative and hypnotic effect of Kava kava and Passiflora extracts combination. Phytomedicine. 2005;12:39-45. PubMed
  10. Carrasco MC, Vallejo JR, Pardo-de-Santayana M, et al. Interactions of Valeriana officinalis L. and Passiflora incarnata L. in a patient treated with lorazepam. Phytother Res. 2009 Dec;23:1795-6.
  11. Smith, G. W., Chalmers, T. M., and Nuki, G. Vasculitis associated with herbal preparation containing Passiflora extract. Br J Rheumatol. 1993;32(1):87-88.
  12. Soulimani, R., Younos, C., Jarmouni, S., Bousta, D., Misslin, R., and Mortier, F. Behavioural effects of Passiflora incarnata L. and its indole alkaloid and flavonoid derivatives and maltol in the mouse. J Ethnopharmacol. 1997;57(1):11-20. PubMed
  13. Nojoumi M, Ghaeli P, Salimi S, Sharifi A, Raisi F. Effects of Passion Flower Extract, as an Add-On Treatment to Sertraline, on Reaction Time in Patients ?with Generalized Anxiety Disorder: A Double-Blind Placebo-Controlled Study. Iran J Psychiatry. 2016;1
  14. Rokhtabnak F, Ghodraty MR, Kholdebarin A, et al. Comparing the Effect of Preoperative Administration of Melatonin and Passiflora incarnata on Postoperative Cognitive Disorders in Adult Patients Undergoing Elective Surgery. Anesth Pain Med. 2016;7(1):e4123 PubMed
  15. Dantas LP, de Oliveira-Ribeiro A, de Almeida-Souza LM, Groppo FC. Effects of passiflora incarnata and midazolam for control of anxiety in patients undergoing dental extraction. Med Oral Patol Oral Cir Bucal. 2017;22(1):e95-e101. 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 Passion Flower and Doxycycline Together: Common Questions

Is it safe to take Passion Flower with Doxycycline?
We do not list a known interaction between Passion Flower and Doxycycline. 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 Passion Flower and Doxycycline have any of the same side effects?
Yes — our sources link each of them separately to 4 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.
Should I take Passion Flower and Doxycycline at the same time of day?
At least one FDA label for a product containing Doxycycline says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Doxycycline on its own and move Passion Flower to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.
How was the Passion Flower and Doxycycline combination checked?
Interactions in our licensed database are recorded against drug classes. Doxycycline is filed under 9 classifications, and Passion Flower has documented interactions with 3 drug classes — none of Doxycycline'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 Passion Flower interact with any other medications?
Yes. Passion Flower has 836 documented drug interactions in our database — Doxycycline 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 Doxycycline interact with any supplements?
Yes. Doxycycline has documented interactions with 166 supplements in our database — Passion Flower is not one of them. The Doxycycline 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

Passion Flower monograph Uses, safety profile, and every drug interaction in one place Doxycycline drug information The full plain-English guide to this medication Doxycycline supplement interactions Every supplement checked against Doxycycline, 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 19 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Doxycycline and Passion Flower?

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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.