Drug & supplement interaction

Threonine + Rifapentine

Rifapentine brand name: Priftin.

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 Threonine and Rifapentine 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 Rifapentine 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

Threonine and Rifapentine

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 Rifapentine and Threonine 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.

Threonine safety at a glance

Threonine overall Use caution Threonine from food is safe; supplement safety at higher doses is not well studied.
Pregnancy Use caution Amounts from food are fine, but supplements have not been well studied in pregnancy, so avoid unless advised by a clinician.
Breastfeeding Use caution Dietary amounts are normal, but supplement use during breastfeeding has not been well studied.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Rifapentine and Threonine? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Rifapentine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Rifapentine is filed under 4 classifications — including cytochrome p450 2c9 (cyp2c9) inducers, cytochrome p450 3a4 (cyp3a4) inducers, antibiotic drugs. Threonine has documented interactions with 1 drug class — the most serious being nmda antagonists (major) — and none of Rifapentine’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

Threonine Does Interact With Other Medications

Threonine has 3 major, known drug interactions in our database — Rifapentine isn’t one of them. If you take anything else, check it against the full list below.

Major 3 No known interaction 2,827 (incl. Rifapentine)
Taking anything else?

Check Another of Your Medications Against Threonine

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

What to actually watch for

No Interaction Found — But Data Suggests Threonine and Rifapentine 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.

  • Stomach upset / Constipation / Diarrhea Additional detail

    Threonine

    “Orally, some patients can experience minor gastrointestinal upset including diarrhea. Other side effects reported in people who have taken threonine include flatus and constipation.”

    Threonine · Natural Medicines adverse-effect record, reported in constipation.

    2 sources cited
    1. 12056. Lee A, Patterson V. A double blind study of L-threonine in patients with spinal spasticity. Acta Neurol Scand 1993;88:334-8. PubMed
    2. 681. Tandan R, Bromberg MB, Forshew D, et al. A controlled trial of amino acid therapy in amyotrophic lateral sclerosis: I. Clinical, functional, and maximum isometric torque data. Neurology 1996;47:1220-6. PubMed

    Rifapentine

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

  • Headache Additional detail

    Threonine

    “Orally, headache has been reported in people who have taken threonine.”

    Threonine · Natural Medicines adverse-effect record, reported in cluster headache.

    1 source cited
    1. 681. Tandan R, Bromberg MB, Forshew D, et al. A controlled trial of amino acid therapy in amyotrophic lateral sclerosis: I. Clinical, functional, and maximum isometric torque data. Neurology 1996;47:1220-6. PubMed

    Rifapentine

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

Effects for Rifapentine come from the ADVERSE REACTIONS section of its FDA label; effects for Threonine 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.

How to take them

Some Rifapentine Products Have a Food Rule — Threonine Should Not Break It

At least one FDA label for a product containing Rifapentine says to take it with food. If you take Threonine on an empty stomach out of habit, keep them separate — and take Rifapentine with a meal where the label says to.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Rifapentine 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.

( 2.2 ) Take with food.

From the Dosage and Administration section of the FDA label we read for Rifapentine — 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.

Everything else you take

See Every Supplement That Interacts With Rifapentine

This page covers Threonine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Rifapentine page lists 64 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Alkanna (moderate), Alpine Ragwort (moderate), Bacillus Coagulans (moderate) and Bacillus Subtilis (moderate).

By severity: 1 major · 53 moderate · 10 minor.

From our pharmacist’s overview on the Rifapentine page

“Rifapentine (Priftin) treats tuberculosis and is often dosed just once or twice a week, so a single blunted dose costs more than it would with a daily pill. That is why I read this list of 64 interacting supplements as a real warning rather than routine fine print.”

Reviewed by 2 · Jul 18, 2026

Open the Rifapentine interaction page

One more smart check

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

We hold 1,803 real supplement products containing Threonine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Threonine. Even though Threonine itself has no known interaction with Rifapentine, 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 Threonine and Rifapentine 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 Threonine
Top 10%

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

29 days ago today
Medication Rifapentine
Steady interest

#2,684 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 Threonine reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Threonine and Rifapentine records this page draws on were last updated July 10, 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 Threonine

What is Threonine?

  • General amino acid/protein support
  • Muscle and tissue health
  • Immune support
  • Nervous system support (as a precursor)
  • Liver health (proposed)

Threonine is an essential amino acid your body needs but cannot make, so you must get it from food or supplements. Most people get plenty from a normal diet, and high-quality evidence for taking it as a separate supplement is limited. If you are considering threonine supplements, talk with your pharmacist or doctor first.

Amino acid (obtained from dietary protein or made synthetically) · Capsules, tablets, powder, and part of amino acid blends; also found in protein-rich foods

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

Threonine: dosing

There is no well-established standard supplement dose of threonine for general health. Studies that have used it for specific medical conditions used different amounts, and those doses were given under medical supervision.If you choose to use a threonine product, follow the directions on the label and do not exceed the recommended amount.

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

Read the full Threonine monograph & all interactions
Medication

About Rifapentine

What Is Rifapentine Used For?

Brand name: Priftin

Rifapentine tablets — sold as Priftin and as rifapentine tablets — are used to treat two forms of tuberculosis caused by Mycobacterium tuberculosis. For active pulmonary TB (a live TB infection in the lungs), it is approved for adults and children 12 years and older. It must always be combined with other anti-TB drugs — never taken alone.

For latent tuberculosis infection (LTBI) — where TB bacteria are in the body but not yet causing illness — it is approved for adults and children 2 years and older who are at high risk of the infection becoming active. For LTBI, it is always taken together with isoniazid, once weekly for 12 weeks. Active TB disease must be ruled out before starting LTBI treatment.

Most-Reported Side Effects for Rifapentine

From FAERS, the FDA’s public side-effect reporting system (509 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fever 66 reports
Nausea 52 reports
Fatigue 42 reports
Hypertension 40 reports
Vomiting 40 reports
See full Rifapentine drug information
Keep checking

Other Drugs & Threonine

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

3Major
0Moderate
0Minor
2,826No known interaction
3 Major 2,826 No interaction
Major

3 interactions

No interaction 2,826 drugs checked — show the list

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

Showing the 60 most looked-up of 2,826 medications checked with no known interaction — see the full Threonine list.

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

Threonine References

The 4 references that drive our Threonine 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. Tandan R, Bromberg MB, Forshew D, et al. A controlled trial of amino acid therapy in amyotrophic lateral sclerosis: I. Clinical, functional, and maximum isometric torque data. Neurology 1996;47:1220-6. PubMed
  2. Lee A, Patterson V. A double blind study of L-threonine in patients with spinal spasticity. Acta Neurol Scand 1993;88:334-8. PubMed
  3. Blin O, Pouget J, Aubrespy G, et al. A double-blind placebo controlled trial of L-threonine in amyotrophic lateral sclerosis. J Neurol 1992;239:79-81.
  4. Roufs JB. L-threonine as a symptomatic treatment for amyotrophic lateral sclerosis (ALS). Med Hypotheses 1991;34:20-3. 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 Threonine and Rifapentine Together: Common Questions

Is it safe to take Threonine with Rifapentine?
We do not list a known interaction between Threonine and Rifapentine. 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 Threonine and Rifapentine 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 Threonine and Rifapentine at the same time of day?
At least one FDA label for a product containing Rifapentine says to take it with food. If you take Threonine on an empty stomach out of habit, keep them separate and take Rifapentine with a meal where the label says to. Food instructions belong to the product rather than the ingredient — two Rifapentine products can differ — so check the directions on your own box. This is about absorption, not an interaction.
How was the Threonine and Rifapentine combination checked?
Interactions in our licensed database are recorded against drug classes. Rifapentine is filed under 4 classifications, and Threonine has documented interactions with 1 drug class — none of Rifapentine'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 Threonine interact with any other medications?
Yes. Threonine has 3 documented drug interactions in our database — Rifapentine 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 Rifapentine interact with any supplements?
Yes. Rifapentine has documented interactions with 64 supplements in our database — Threonine is not one of them. The Rifapentine 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

Threonine monograph Uses, safety profile, and every drug interaction in one place Rifapentine drug information The full plain-English guide to this medication Rifapentine supplement interactions Every supplement checked against Rifapentine, 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 4 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Rifapentine and Threonine?

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.