Drug & supplement interaction

Blackthorn + 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 Blackthorn 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

Blackthorn 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 Blackthorn 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 Blackthorn at all — not against Doxycycline, 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.

Blackthorn safety at a glance

Blackthorn overall Use caution Culinary amounts of the fruit are generally well tolerated, but medicinal use is not well studied.
Pregnancy Possibly Unsafe When the seeds or fresh flowers are used orally; avoid using. The seeds and fresh flowers contain small amounts of the cyanogenic glycoside amygdalin, which can... Read the full pregnancy detail
Breastfeeding Avoid Safety has not been established, so avoid medicinal use 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.

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

No Interaction Found — But Data Suggests Blackthorn and Doxycycline 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.

  • A skin rash Additional detail

    Blackthorn

    “Avoid contact with the thorns on blackthorn branches. They can break off and become embedded in the deep layers of the skin, the tendons, or in the small joints of the fingers, requiring surgical removal. When left embedded they can cause cysts, abscesses, dermatitis, cellulitis, foreign body granuloma, chronic inflammation, tendinitis, synovitis, and septic arthritis.”

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

    2 sources cited
    1. 100919. Sharma H, Meredith AD. Blackthorn injury: a report of three interesting cases. Emerg Med J 2004;21(3):392. PubMed
    2. 100920. Sharma H, Meredith AD. A report of 18 blackthorn injuries of the upper limb. Injury 2004;35(9):930-5. PubMed

    Doxycycline

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

Reported for Blackthorn but not commonly for Doxycycline: joint pain.

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

Blackthorn in Pregnancy & Breastfeeding

Pregnancy Possibly Unsafe

When the seeds or fresh flowers are used orally; avoid using. The seeds and fresh flowers contain small amounts of the cyanogenic glycoside amygdalin, which can be teratogenic.

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 — Blackthorn Should Not Break It

At least one FDA label for a product containing Doxycycline says to take it on an empty stomach. Most supplements — Blackthorn 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 Blackthorn 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 Blackthorn 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 Blackthorn 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 Blackthorn 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 Blackthorn as Part of a Dietary Supplement Product? Check It for Interactions

We hold 2 real supplement products containing Blackthorn, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Blackthorn. Even though Blackthorn 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 Blackthorn 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 Blackthorn
Top half

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

29 days ago today
Medication Doxycycline
Top 5%

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

What is Blackthorn?

  • Digestive upset
  • Mild constipation
  • Cold and cough symptoms
  • Mouth and throat irritation
  • Mild diuretic ('blood cleansing') tonic

Blackthorn is a thorny shrub whose flowers and dark blue-black fruit (sloes) are used in traditional European herbal medicine, mostly for digestive complaints and as a mild tonic. Solid human research is lacking, so its benefits are not proven, though small culinary amounts of the fruit are generally considered safe. Talk to your pharmacist or doctor before using it, especially if you are pregnant, breastfeeding, or taking other medicines.

Prunus spinosa · Rosaceae · Flowers, fruit (sloes), leaves, and bark · Tea, syrup, juice, tincture, jam/preserves, and liqueur (sloe gin)

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

Blackthorn: dosing

There is no established or standardized medicinal dose for blackthorn. Traditional use varies widely depending on whether the flowers, fruit, or other parts are used and how they are prepared.If you choose to use a commercial blackthorn product, follow the directions on the label and do not exceed the recommended amount. Avoid making your own preparations from the seeds, leaves, or bark.

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

Read the full Blackthorn 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 & Blackthorn

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

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

Blackthorn References

The 3 references that drive our Blackthorn 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. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  2. Sharma H, Meredith AD. Blackthorn injury: a report of three interesting cases. Emerg Med J 2004;21(3):392. PubMed
  3. Sharma H, Meredith AD. A report of 18 blackthorn injuries of the upper limb. Injury 2004;35(9):930-5. 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 Blackthorn and Doxycycline Together: Common Questions

Is it safe to take Blackthorn with Doxycycline?
We do not list a known interaction between Blackthorn 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 Blackthorn and Doxycycline 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.
Should I take Blackthorn 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 Blackthorn 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.
Does Doxycycline interact with any supplements?
Yes. Doxycycline has documented interactions with 166 supplements in our database — Blackthorn 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

Blackthorn 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 3 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Doxycycline and Blackthorn?

Our pharmacists answer your medication & supplement questions — free.

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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.