Drug & supplement interaction

Hemlock + Glycerol Phenylbutyrate

Glycerol Phenylbutyrate brand name: Ravicti.

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 Hemlock and Glycerol Phenylbutyrate 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 Glycerol Phenylbutyrate 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

Hemlock and Glycerol Phenylbutyrate

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 Glycerol Phenylbutyrate and Hemlock 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 Hemlock at all — not against Glycerol Phenylbutyrate, 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.

Hemlock safety at a glance

Hemlock overall Avoid Hemlock is a deadly poison and should never be taken in any amount.
Pregnancy Unsafe When used orally because ingestion can be lethal; avoid using. Read the full pregnancy detail
Breastfeeding Unsafe When used orally because ingestion can be lethal; avoid using. 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 Glycerol Phenylbutyrate and Hemlock? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Hemlock and Glycerol Phenylbutyrate 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.

  • Vomiting reported in 12.2% of FDA reports for Glycerol Phenylbutyrate Additional detail

    Hemlock

    “Hemlock is generally regarded as unsafe for use. Any benefits of therapy may not outweigh the risk of toxicity. Orally, hemlock can cause burning of the mouth, throat, and abdomen, nausea, vomiting, excessive urination, salivation, drowsiness, mydriasis, muscle pain, rapid muscle swelling and stiffness, rhabdomyolysis, and tachycardia followed by bradycardia.”

    Hemlock · Natural Medicines adverse-effect record, reported in muscle breakdown.

    6 sources cited
    1. 6340. Drummer OH, Roberts AN, Bedford PJ, et al. Three deaths from hemlock poisoning. Med J Aust 1995;162:592-3. PubMed
    2. 6341. Frank BS, Panter KE. Ingestion of poison hemlock (Conium maculatum). West J Med 1995;163:573-4.
    3. 54709. Biberci, E., Altuntas, Y., Cobanoglu, A., and Alpinar, A. Acute respiratory arrest following hemlock (Conium maculatum) intoxication. J.Toxicol.Clin.Toxicol. 2002;40(4):517-518.
    4. 54711. Foster, P. F., McFadden, R., Trevino, R., Galliardt, S., Kopczewski, L. A., Gugliuzza, K., Gonzalez, Z., and Wright, F. Successful transplantation of donor organs from a hemlock poisoning victim. Transplantation 9-15-2003;76(5):874-876. PubMed
    5. 54712. Vetter, J. Poison hemlock (Conium maculatum L.). Food Chem.Toxicol. 2004;42(9):1373-1382. PubMed
    6. 54716. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Scatizzi, A., De Marco, S., and Smialek, J. E. Clinical spectrum of accidental hemlock poisoning: neurotoxic manifestations, rhabdomyolysis and acute tubular necrosis. Nephr PubMed

    “Orally, hemlock can cause drowsiness, fatigue, lethargy, dizziness, numbness, loss of speech, tremors, paralysis, seizures, encephalopathy, unconsciousness, and death. Death from hemlock toxicity is usually due to respiratory paralysis.

    A case report describes prolonged status epilepticus in a 41-year-old, previously healthy female who mistook hemlock root for parsnip.”

    Hemlock · Natural Medicines adverse-effect record, reported in epilepsy.

    6 sources cited
    1. 6340. Drummer OH, Roberts AN, Bedford PJ, et al. Three deaths from hemlock poisoning. Med J Aust 1995;162:592-3. PubMed
    2. 6341. Frank BS, Panter KE. Ingestion of poison hemlock (Conium maculatum). West J Med 1995;163:573-4.
    3. 10778. Carod-Artal FJ. [Neurological syndromes linked with the intake of plants and fungi containing a toxic component (I). Neurotoxic syndromes caused by the ingestion of plants, seeds and fruits]. Rev Neurol 2003;36:860-71.
    4. 54711. Foster, P. F., McFadden, R., Trevino, R., Galliardt, S., Kopczewski, L. A., Gugliuzza, K., Gonzalez, Z., and Wright, F. Successful transplantation of donor organs from a hemlock poisoning victim. Transplantation 9-15-2003;76(5):874-876. PubMed
    5. 54712. Vetter, J. Poison hemlock (Conium maculatum L.). Food Chem.Toxicol. 2004;42(9):1373-1382. PubMed
    6. 54716. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Scatizzi, A., De Marco, S., and Smialek, J. E. Clinical spectrum of accidental hemlock poisoning: neurotoxic manifestations, rhabdomyolysis and acute tubular necrosis. Nephr PubMed

    Glycerol Phenylbutyrate

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

  • Tiredness / Dizziness Additional detail

    Hemlock

    Recorded for Hemlock in the same Natural Medicines adverse-effect record shown under Vomiting above.

    Glycerol Phenylbutyrate

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

  • Nausea reported in 5.4% of FDA reports for Glycerol Phenylbutyrate Additional detail

    Hemlock

    “Orally, hemlock causes burning of the mouth, throat, and abdomen. It can also cause nausea, vomiting, and increased salivation.”

    Hemlock · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    5 sources cited
    1. 6341. Frank BS, Panter KE. Ingestion of poison hemlock (Conium maculatum). West J Med 1995;163:573-4.
    2. 96877. Konca C, Kahramaner Z, Bosnak M, Kocamaz H. Hemlock (Conium Maculatum) poisoning in a child. Turk J Emerg Med. 2016;14(1):34-6. DOI
    3. 54712. Vetter, J. Poison hemlock (Conium maculatum L.). Food Chem.Toxicol. 2004;42(9):1373-1382. PubMed
    4. 96878. Chen HY, Horng H, Rowley F, Smollin C. Rapid respiratory arrest after ingestion of poison hemlock mistaken for wild celery. Clin Toxicol (Phila). 2017;55(2):155-156. PubMed
    5. 110410. Boskabadi J, Askari Z, Zakariaei Z, Fakhar M, Tabaripour R. Mild-to-severe poisoning due to Conium maculatum as toxic herb: A case series. Clin Case Rep. 2021 Jul 23;9(7):e04509.

    Glycerol Phenylbutyrate

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

Reported for Hemlock but not commonly for Glycerol Phenylbutyrate: seizures, kidney problems, severe muscle breakdown and raised blood pressure.

Effects for Glycerol Phenylbutyrate come from the ADVERSE REACTIONS section of its FDA label; effects for Hemlock come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 1,358 voluntary FDA FAERS reports for Glycerol Phenylbutyrate 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.

Special populations

Hemlock in Pregnancy & Breastfeeding

Pregnancy And Lactation Unsafe

When used orally because ingestion can be lethal; avoid using.

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 Glycerol Phenylbutyrate Products Have a Food Rule — Hemlock Should Not Break It

At least one FDA label for a product containing Glycerol Phenylbutyrate says to take it with food. If you take Hemlock on an empty stomach out of habit, keep them separate — and take Glycerol Phenylbutyrate 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 Glycerol Phenylbutyrate 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.

Instruct patients to take glycerol phenylbutyrate oral liquid with food or formula and to administer directly into the mouth via oral syringe.

From the Dosage and Administration section of the FDA label we read for Glycerol Phenylbutyrate — 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 Glycerol Phenylbutyrate

This page covers Hemlock only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Glycerol Phenylbutyrate page lists 17 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).

By severity: 1 major · 7 moderate · 9 minor.

From our pharmacist’s overview on the Glycerol Phenylbutyrate page

“Ravicti (glycerol phenylbutyrate) pulls ammonia out of the blood in people with urea cycle disorders, so a dose that never gets absorbed is not a small problem, it can let ammonia climb toward dangerous levels. That is why this list deserves real attention even though it is short.”

Reviewed by 2 · Jul 18, 2026

Open the Glycerol Phenylbutyrate interaction page

One more smart check

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

We hold 9 real supplement products containing Hemlock, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Hemlock. Even though Hemlock itself has no known interaction with Glycerol Phenylbutyrate, 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 Hemlock and Glycerol Phenylbutyrate 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 Hemlock
Steady interest

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

29 days ago today
Medication Glycerol Phenylbutyrate
Top 25%

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

What is Hemlock?

  • Historical sedative or pain reliever
  • Traditional treatment for muscle spasms
  • Folk use for joint and nerve pain
  • Historical execution poison
  • Homeopathic preparations

Hemlock (Conium maculatum) is a highly poisonous plant that has no safe or proven medicinal use today. Even small amounts can cause paralysis and death, so it should never be consumed or applied to the body. Do not use hemlock or any product containing it.

Conium maculatum · Apiaceae · Whole plant, including leaves, seeds, stems, and roots (all parts are poisonous) · Not safely used in any form; historically prepared as extracts, tinctures, or poultices

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

Hemlock: dosing

There is no safe dose of hemlock. It is not a supplement and should never be measured out or taken. Even a small amount of plant material or seeds can be fatal to humans and animals.Do not buy, prepare, or consume any product that contains Conium maculatum.

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

Read the full Hemlock monograph & all interactions
Medication

About Glycerol Phenylbutyrate

What Is Glycerol Phenylbutyrate Used For?

Brand name: Ravicti

Glycerol phenylbutyrate oral liquid — available as the brand Ravicti and as a generic — is used for the long-term (chronic) management of urea cycle disorders (UCDs). UCDs are rare inherited conditions where the body cannot properly convert ammonia into urea, causing toxic ammonia levels to build up in the blood and brain.

It is used in patients whose ammonia cannot be controlled by a low-protein diet and/or amino acid supplements alone. It must always be used alongside dietary protein restriction and, in some cases, additional dietary supplements such as essential amino acids, arginine, or citrulline. It is not for treating a sudden, severe spike in ammonia (acute hyperammonemia), and its safety and effectiveness for N-acetylglutamate synthase (NAGS) deficiency have not been established.

Most-Reported Side Effects for Glycerol Phenylbutyrate

From FAERS, the FDA’s public side-effect reporting system (1,358 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Ammonia increased 197 reports
Vomiting 165 reports
Hyperammonaemia 158 reports
Decreased appetite 104 reports
Nausea 74 reports
See full Glycerol Phenylbutyrate drug information
Keep checking

Other Drugs & Hemlock

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

See the full Hemlock interactions page
See every supplement checked against Glycerol Phenylbutyrate, ranked by severity
Evidence & sources

Hemlock References

The 18 references that drive our Hemlock 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. Lopez TA, Cid MS, Bianchini ML. Biochemistry of hemlock (Conium maculatum L.) alkaloids and their acute and chronic toxicity in livestock. A review. Toxicon 1999;37:841-65. PubMed
  2. Drummer OH, Roberts AN, Bedford PJ, et al. Three deaths from hemlock poisoning. Med J Aust 1995;162:592-3. PubMed
  3. Frank BS, Panter KE. Ingestion of poison hemlock (Conium maculatum). West J Med 1995;163:573-4.
  4. Carod-Artal FJ. [Neurological syndromes linked with the intake of plants and fungi containing a toxic component (I). Neurotoxic syndromes caused by the ingestion of plants, seeds and fruits]. Rev Neurol 2003;36:860-71.
  5. Biberci, E., Altuntas, Y., Cobanoglu, A., and Alpinar, A. Acute respiratory arrest following hemlock (Conium maculatum) intoxication. J.Toxicol.Clin.Toxicol. 2002;40(4):517-518.
  6. Foster, P. F., McFadden, R., Trevino, R., Galliardt, S., Kopczewski, L. A., Gugliuzza, K., Gonzalez, Z., and Wright, F. Successful transplantation of donor organs from a hemlock poisoning victim. Transplantation 9-15-2003;76(5):874-876. PubMed
  7. Vetter, J. Poison hemlock (Conium maculatum L.). Food Chem.Toxicol. 2004;42(9):1373-1382. PubMed
  8. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Scatizzi, A., De Marco, S., and Smialek, J. E. Clinical spectrum of accidental hemlock poisoning: neurotoxic manifestations, rhabdomyolysis and acute tubular necrosis. Nephr PubMed
  9. Rizzi, D., Basile, C., Di Maggio, A., Sebastio, A., Introna, F., Jr., Rizzi, R., Bruno, S., Scatizzi, A., and De Marco, S. Rhabdomyolysis and acute tubular necrosis in coniine (hemlock) poisoning. Lancet 12-16-1989;2(8677):1461-1462. PubMed
  10. Rizzi, D., Introna, F., Jr., Gagliano, Candela R., Di Nunno, C., Ricco, R., Recchia, R., and De, Michele, V. [Toxic rhabdomyolysis and tubular necrosis in hemlock poisoning. 4 case reports]. Clin.Ter. 2-15-1988;124(3):193-201.
  11. Montemurro, N. E., Di Maggio, A., Strippoli, P., Coviello, F., Godino, F., Miloro, G., and Scatizzi, A. Combined dialysis and plasma-exchange in acute renal failure. Biomater.Artif.Cells Immobilization Biotechnol. 1993;21(2):283-287. PubMed
  12. Scatizzi, A., Di Maggio, A., Rizzi, D., Sebastio, A. M., and Basile, C. Acute renal failure due to tubular necrosis caused by wildfowl-mediated hemlock poisoning. Ren Fail. 1993;15(1):93-96. PubMed
  13. Brtalik D, Stopyra J, Hannum J. Intravenous poison hemlock injection resulting in prolonged respiratory failure and encephalopathy. J Med Toxicol. 2017;13(2):180-182. PubMed
  14. Konca C, Kahramaner Z, Bosnak M, Kocamaz H. Hemlock (Conium Maculatum) poisoning in a child. Turk J Emerg Med. 2016;14(1):34-6. DOI
  15. Chen HY, Horng H, Rowley F, Smollin C. Rapid respiratory arrest after ingestion of poison hemlock mistaken for wild celery. Clin Toxicol (Phila). 2017;55(2):155-156. 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 Hemlock and Glycerol Phenylbutyrate Together: Common Questions

Is it safe to take Hemlock with Glycerol Phenylbutyrate?
We do not list a known interaction between Hemlock and Glycerol Phenylbutyrate. 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 Hemlock and Glycerol Phenylbutyrate 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 Hemlock and Glycerol Phenylbutyrate at the same time of day?
At least one FDA label for a product containing Glycerol Phenylbutyrate says to take it with food. If you take Hemlock on an empty stomach out of habit, keep them separate and take Glycerol Phenylbutyrate with a meal where the label says to. Food instructions belong to the product rather than the ingredient — two Glycerol Phenylbutyrate products can differ — so check the directions on your own box. This is about absorption, not an interaction.
Does Glycerol Phenylbutyrate interact with any supplements?
Yes. Glycerol Phenylbutyrate has documented interactions with 17 supplements in our database — Hemlock is not one of them. The Glycerol Phenylbutyrate 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

Hemlock monograph Uses, safety profile, and every drug interaction in one place Glycerol Phenylbutyrate drug information The full plain-English guide to this medication Glycerol Phenylbutyrate supplement interactions Every supplement checked against Glycerol Phenylbutyrate, 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 18 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Glycerol Phenylbutyrate and Hemlock?

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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.