Drug & supplement interaction

L-ornithine-l-aspartate + Trimethoprim

Trimethoprim brand names: Proloprim, Trimpex.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 27, 2026
The bottom line No known interaction

We found no known interaction between L-ornithine-l-aspartate and Trimethoprim 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

L-ornithine-l-aspartate and Trimethoprim

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 Trimethoprim and L-ornithine-l-aspartate 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 L-ornithine-l-aspartate at all — not against Trimethoprim, 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.

L-ornithine-l-aspartate safety at a glance

L-ornithine-l-aspa... overall Use caution Generally used under medical supervision for liver disease; self-treating serious liver problems is not advised.
Pregnancy Avoid Safety has not been established in pregnancy, so it is best avoided unless a doctor directs otherwise.
Breastfeeding Avoid There is not enough safety information during breastfeeding, so avoid unless advised by your doctor.

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

Still wondering about combining Trimethoprim and L-ornithine-l-aspartate? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests L-ornithine-l-aspartate and Trimethoprim 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.

  • Nausea / Vomiting reported in 6.0% of FDA reports for Trimethoprim Additional detail

    L-ornithine-l-aspartate

    “Intravenously, L-ornithine-L-aspartate has caused nausea and vomiting, and, less frequently, diarrhea. Slowing down the rate of infusion can prevent nausea and vomiting.”

    L-ornithine-l-aspartate · Natural Medicines adverse-effect record, reported in diarrhea.

    3 sources cited
    1. 67394. Ahmad, I., Khan, A. A., Alam, A., Dilshad, A., Butt, A. K., Shafqat, F., Malik, K., and Sarwar, S. L-ornithine-L-aspartate infusion efficacy in hepatic encephalopathy. J.Coll.Physicians Surg.Pak. 2008;18(11):684-687.
    2. 94907. Waghray A, Waghray N, Mullen K. Management of covert hepatic encephalopathy. J Clin Exp Hepatol 2015;5:S75-81. PubMed
    3. 94911. Pérez Hernández JL, Higuera de la Tijera F, Serralde-Zúñiga AE, Abdo Francis JM. Critical analysis of studies evaluating the efficacy of infusion of L-ornithine L-aspartate in clinical hepatic encephalopathy in patients with liver failure. Ann Hepatol 201

    Trimethoprim

    Listed in the ADVERSE REACTIONS section of the FDA label for Trimethoprim, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

Reported for L-ornithine-l-aspartate but not commonly for Trimethoprim: muscle pain, diarrhea and cough.

Effects for Trimethoprim come from the ADVERSE REACTIONS section of its FDA label; effects for L-ornithine-l-aspartate come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 93,588 voluntary FDA FAERS reports for Trimethoprim that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

From our Q&A

Questions About L-ornithine-l-aspartate or Trimethoprim

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers L-ornithine-l-aspartate or Trimethoprim, 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 Trimethoprim

This page covers L-ornithine-l-aspartate only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Trimethoprim page lists 59 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Cesium (major) and Ephedra (major).

By severity: 7 major · 41 moderate · 11 minor.

From our pharmacist’s overview on the Trimethoprim page

“Most prescriptions for trimethoprim are short courses for bladder infections, which makes it easy to assume nothing swallowed alongside it matters much. Seven of the 59 supplement and herbal ingredients here rate major, though, and nearly all of them involve heart rhythm: grapefruit in large amounts, ephedra, and a few others can prolo…”

Reviewed by 2 · Jul 18, 2026

Open the Trimethoprim interaction page

One more smart check

Taking L-ornithine-l-aspartate as Part of a Dietary Supplement Product? Check It for Interactions

We hold 92 real supplement products containing L-ornithine-l-aspartate, each one broken down to its full ingredient list — and combination products often carry several ingredients besides L-ornithine-l-aspartate. Even though L-ornithine-l-aspartate itself has no known interaction with Trimethoprim, 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 L-ornithine-l-aspartate and Trimethoprim 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 L-ornithine-l-aspartate
Steady interest

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

29 days ago today
Medication Trimethoprim
Steady interest

#1,695 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 L-ornithine-l-aspartate reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 27, 2026. The L-ornithine-l-aspartate and Trimethoprim 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 L-ornithine-l-aspartate

What is L-ornithine-l-aspartate?

L-ornithine-l-aspartate
  • Liver-related brain symptoms (hepatic encephalopathy)
  • Lowering blood ammonia levels
  • Support in cirrhosis and fatty liver
  • General liver support

L-ornithine-L-aspartate (LOLA) is a combination of two amino acids studied mainly for lowering ammonia in people with liver disease and helping manage hepatic encephalopathy. There is reasonable clinical evidence for this specific medical use, but it should be used under medical supervision rather than as a casual 'liver detox' supplement. Talk to your doctor or pharmacist before using it, especially if you have liver or kidney problems.

Oral granules/powder, tablets, oral solution, and intravenous infusion (in clinical settings)

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

L-ornithine-l-aspartate: dosing

There is no single standardized over-the-counter dose for L-ornithine-L-aspartate, and the amounts used in studies were often given in a hospital or clinical setting. Oral and IV forms are dosed differently, and the right amount depends on the condition being treated.If you are using a supplement product, follow the directions on the label and do not exceed them.

From our L-ornithine-l-aspartate monograph — the full record covers uses, side effects and every documented interaction.

Read the full L-ornithine-l-aspartate monograph & all interactions
Medication

About Trimethoprim

What Is Trimethoprim Used For?

Brand names: Proloprim, Trimpex

Trimethoprim tablets are used to treat initial episodes of uncomplicated urinary tract infections (UTIs). It works against specific bacteria — including E. coli, Proteus mirabilis, Klebsiella pneumoniae, Enterobacter species, and coagulase-negative Staphylococcus species (including S. saprophyticus).

It should only be used when there is a proven or strongly suspected bacterial infection. Your doctor may order a urine culture to confirm which bacteria are present and whether trimethoprim will work against them.

See full Trimethoprim drug information
Keep checking

Other Drugs & L-ornithine-l-aspartate

Browse every other medication we’ve checked against L-ornithine-l-aspartate — 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 L-ornithine-l-aspartate 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 L-ornithine-l-aspartate list.

See the full L-ornithine-l-aspartate interactions page
See every supplement checked against Trimethoprim, ranked by severity
Evidence & sources

L-ornithine-l-aspartate References

The 3 references that drive our L-ornithine-l-aspartate 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. Ahmad, I., Khan, A. A., Alam, A., Dilshad, A., Butt, A. K., Shafqat, F., Malik, K., and Sarwar, S. L-ornithine-L-aspartate infusion efficacy in hepatic encephalopathy. J.Coll.Physicians Surg.Pak. 2008;18(11):684-687.
  2. Waghray A, Waghray N, Mullen K. Management of covert hepatic encephalopathy. J Clin Exp Hepatol 2015;5:S75-81. PubMed
  3. Pérez Hernández JL, Higuera de la Tijera F, Serralde-Zúñiga AE, Abdo Francis JM. Critical analysis of studies evaluating the efficacy of infusion of L-ornithine L-aspartate in clinical hepatic encephalopathy in patients with liver failure. Ann Hepatol 201

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 L-ornithine-l-aspartate and Trimethoprim Together: Common Questions

Is it safe to take L-ornithine-l-aspartate with Trimethoprim?
We do not list a known interaction between L-ornithine-l-aspartate and Trimethoprim. 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 L-ornithine-l-aspartate and Trimethoprim 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.
Does Trimethoprim interact with any supplements?
Yes. Trimethoprim has documented interactions with 59 supplements in our database — L-ornithine-l-aspartate is not one of them. The Trimethoprim 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

L-ornithine-l-aspartate monograph Uses, safety profile, and every drug interaction in one place Trimethoprim drug information The full plain-English guide to this medication Trimethoprim supplement interactions Every supplement checked against Trimethoprim, 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 Trimethoprim and L-ornithine-l-aspartate?

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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.