Drug & supplement interaction

Vitamin E + 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 Vitamin E 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

Vitamin E 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 Vitamin E 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.

Vitamin E safety at a glance

Vitamin E overall Use caution Usual dietary amounts are safe, but high-dose long-term supplements may raise the risk of bleeding and other harms.
Pregnancy Possibly Safe When used orally and appropriately. The tolerable upper intake level (UL) during pregnancy is 800 mg for those 14-18 years of age and 1000 mg for those 19 years... Read the full pregnancy detail
Breastfeeding Likely Safe When used orally in amounts that do not exceed the tolerable upper intake level (UL). The UL during lactation is 800 mg for those 14-18 years of age and 1000 mg... 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 Vitamin E? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Glycerol Phenylbutyrate

Interactions in our licensed database are recorded against drug classes, not just single drug names. Glycerol Phenylbutyrate is filed under a single classification — oral drugs. Vitamin E has documented interactions with 8 drug classes — the most serious being alkylating agents (moderate), anticoagulant/antiplatelet drugs (moderate) and antitumor antibiotics (moderate) — and none of Glycerol Phenylbutyrate’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

Vitamin E Does Interact With Other Medications

Vitamin E has 763 moderate, 1 minor known drug interactions in our database — Glycerol Phenylbutyrate isn’t one of them. If you take anything else, check it against the full list below.

Moderate 763 Minor 1 No known interaction 2,066 (incl. Glycerol Phenylbutyrate)
Taking anything else?

Check Another of Your Medications Against Vitamin E

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

What to actually watch for

No Interaction Found — But Data Suggests Vitamin E 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.

  • Stomach pain / Diarrhea / Nausea reported in 5.4% of FDA reports for Glycerol Phenylbutyrate Additional detail

    Vitamin E

    “Orally, vitamin E supplementation has been associated with abdominal pain, nausea, diarrhea, or flu-like symptoms. Intravenously, large doses of vitamin E in premature infants are associated with an increased risk of necrotizing enterocolitis and sepsis.”

    Vitamin E · Natural Medicines adverse-effect record, reported in diarrhea.

    4 sources cited
    1. 85040. Soares, K. V. and McGrath, J. J. Vitamin E for neuroleptic-induced tardive dyskinesia. Cochrane.Database.Syst.Rev. 2001;(4):CD000209. DOI
    2. 85323. Barak, Y., Swartz, M., Shamir, E., Stein, D., and Weizman, A. Vitamin E (alpha-tocopherol) in the treatment of tardive dyskinesia: a statistical meta-analysis. Ann.Clin.Psychiatry 1998;10(3):101-105.
    3. 85083. Brion, L. P., Bell, E. F., Raghuveer, T. S., and Soghier, L. What is the appropriate intravenous dose of vitamin E for very-low-birth-weight infants? J.Perinatol. 2004;24(4):205-207. PubMed
    4. 85231. Bell, E. F. Upper limit of vitamin E in infant formulas. J.Nutr. 1989;119(12 Suppl):1829-1831. 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 ›

  • A skin rash Additional detail

    Vitamin E

    “Topically, vitamin E has been associated with contact dermatitis, inflammatory reactions, and eczematous lesions. Dermatitis, often associated with moisturizers containing vitamin E, has a scattered generalized distribution, is more common on the face than the hands, and is more common in females with a history of atopic dermatitis.”

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

    6 sources cited
    1. 11998. Brodkin RH, Bleiberg J. Sensitivity to topically applied vitamin E. Arch Dermatol 1965;92:76-7. DOI
    2. 85066. Roed-Petersen, J. and Hjorth, N. Contact dermatitis from antioxidants. Br.J.Dermatol. 1976;94(3):233-241. PubMed
    3. 85285. Manzano, D., Aguirre, A., Gardeazabal, J., Eizaguirre, X., and Diaz Perez, J. L. Allergic contact dermatitis from tocopheryl acetate (vitamin E) and retinol palmitate (vitamin A) in a moisturizing cream. Contact Dermatitis 1994;31(5):324.
    4. 107869. Warshaw EM, Ruggiero JL, DeKoven JG, et al. Patch testing with tocopherol and tocopherol acetate: the North American Contact Dermatitis Group experience, 2001 to 2016. Dermatitis. 2021;32(5):308-18. PubMed
    5. 34596. Cooper, K., Squires, H., Carroll, C., Papaioannou, D., Booth, A., Logan, R. F., Maguire, C., Hind, D., and Tappenden, P. Chemoprevention of colorectal cancer: systematic review and economic evaluation. Health Technol.Assess. 2010;14(32):1-206. PubMed
    6. 85188. Manny, T., Pettus, J., Hemal, A., Marks, M., and Mirzazadeh, M. Penile sclerosing lipogranulomas and disfigurement from use of "1Super Extenze" among Laotian immigrants. J.Sex Med. 2011;8(12):3505-3510. PubMed

    Glycerol Phenylbutyrate

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

Reported for Vitamin E but not commonly for Glycerol Phenylbutyrate: a heart attack, a stroke or mini-stroke, heart failure and raised blood pressure.

Effects for Glycerol Phenylbutyrate come from the ADVERSE REACTIONS section of its FDA label; effects for Vitamin E 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

Vitamin E in Pregnancy & Breastfeeding

Pregnancy Possibly Safe

When used orally and appropriately. The tolerable upper intake level (UL) during pregnancy is 800 mg for those 14-18 years of age and 1000 mg for those 19 years and older. However, maternal supplementation is not generally recommended unless dietary vitamin E falls below the RDA. No serious adverse effects were reported with oral intake of 400 IU per day starting at weeks 9-22 of pregnancy in healthy patients or those at high risk for pre-eclampsia, or with 600-900 IU daily during the last two months of pregnancy. However, some preliminary evidence suggests that taking vitamin E supplements might be harmful when taken in early pregnancy. A case-control study found that taking a vitamin E supplement during the first 8 weeks of pregnancy is associated with a 1.7-9-fold increase in odds of congenital heart defects. However, the exact amount of vitamin E consumed during pregnancy in this study is unclear. Until more is known, advise patients to avoid taking a vitamin E supplement in early pregnancy unless needed for an appropriate medical indication.

Lactation Likely Safe

When used orally in amounts that do not exceed the tolerable upper intake level (UL). The UL during lactation is 800 mg for those 14-18 years of age and 1000 mg for those 19 years and older.

Lactation Possibly Unsafe

When used orally in amounts that exceed the UL due to increased risk of adverse effects.

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 — Vitamin E Should Not Break It

At least one FDA label for a product containing Glycerol Phenylbutyrate says to take it with food. If you take Vitamin E 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 Vitamin E 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 Vitamin E as Part of a Dietary Supplement Product? Check It for Interactions

We hold 22,182 real supplement products containing Vitamin E, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Vitamin E. Even though Vitamin E 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 Vitamin E 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 Vitamin E
Top 10

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

29 days ago today
Medication Glycerol Phenylbutyrate
Top half

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

What is Vitamin E?

Vitamin E
  • General antioxidant support
  • Skin and hair care
  • Heart health
  • Eye health (age-related conditions)
  • Immune support

Vitamin E is an essential fat-soluble vitamin and antioxidant that most people get in adequate amounts from a normal diet. Supplements can help correct a true deficiency, but high-dose vitamin E has not been clearly proven to prevent heart disease or cancer and may carry risks. Talk to your pharmacist or doctor before taking high doses.

Vitamin E is a nutrient, not a plant part; it is found in plant oils, nuts, seeds, and leafy greens · Softgels, capsules, oral liquid, chewable tablets, topical oils and creams

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

Vitamin E: dosing

Vitamin E needs are usually met through a normal diet. There is a recommended daily intake set by health authorities, and there is also an upper limit for supplements that should not be exceeded without medical guidance, because higher amounts raise the risk of side effects.Because the right amount depends on your age, health, and diet, it is best to follow the product label and avoid high-dose products unless a healthcare provider recommends them.

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

Read the full Vitamin E 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 & Vitamin E

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

0Major
763Moderate
1Minor
2,065No known interaction
763 Moderate 1 Minor 2,065 No interaction
Moderate

763 interactions

Showing 60 of 763 moderate interactions — see all 763 on the Vitamin E page.

Minor

1 interaction

No interaction 2,065 drugs checked — show the list

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

Showing the 60 most looked-up of 2,065 medications checked with no known interaction — see the full Vitamin E list.

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

Vitamin E References

The 64 references that drive our Vitamin E 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. Kim JM, White RH. Effect of vitamin E on the anticoagulant response to warfarin. Am J Cardiol 1996;77:545-6. PubMed
  2. Corrigan JJ Jr. The effect of vitamin E on warfarin-induced vitamin K deficiency. Ann N Y Acad Sci 1982;393:361-8. PubMed
  3. Corrigan JJ Jr. Coagulation problems relating to vitamin E. Am J Pediatr Hematol Oncol 1979;1:169-73.
  4. Corrigan JJ Jr, Marcus FI. Coagulopathy associated with vitamin E ingestion. JAMA 1974;230:1300-1. DOI
  5. Labriola D, Livingston R. Possible interactions between dietary antioxidants and chemotherapy. Oncology 1999;13:1003-8.
  6. Chang T, Benet LZ, Hebert MF. The effect of water-soluble vitamin E on cyclosporine pharmacokinetics in healthy volunteers. Clin Pharmacol Ther 1996;59:297-303. PubMed
  7. Pan SH, Lopez RR Jr, Sher LS, et al. Enhanced oral cyclosporine absorption with water-soluble vitamin E early after liver transplantation. Pharmacother 1996;16:59-65. DOI
  8. Anon. Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Gruppo Italiano per lo Studio della Soprawivenza nell'Infarto miocardico. Lancet 1999;354:447-55. DOI
  9. Chappell LC, Seed PT, Briley AL, et al. Effect of antioxidants on the occurrence of pre-eclampsia in women at increased risk: a randomised trial. Lancet 1999;354:810-6. DOI
  10. Yusuf S, Dagenais G, Pogue J, et al. Vitamin E supplementation and cardiovascular events in high-risk patients. The heart outcomes prevention evaluation study investigators. N Engl J Med 2000;342:154-60. PubMed
  11. Stephens NG, Parsons A, Schofield PM, et al. Randomised controlled trial of vitamin E in patients with coronary disease: Cambridge Heart Antioxidant Study. Lancet 1996;347:781-6.
  12. The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group. The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. N Engl J Med 1994;330:1029-35. PubMed
  13. Takahashi O. Haemorrhagic toxicity of a large dose of alpha-, beta-, gamma- and delta-tocopherols, ubiquinone, beta-carotene, retinol acetate and L-ascorbic acid in the rat. Food Chem Toxicol 1995;33:121-8.
  14. Briggs GB, Freeman RK, Yaffe SJ. Drugs in Pregnancy and Lactation. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 1998.
  15. Sano M, Ernesto C, Thomas RG, et al. A controlled trial of selegiline, alpha-tocopherol, or both as treatment for Alzheimer's disease. The Alzheimer's Disease Cooperative Study. N Engl J Med 1997;336:1216-22. 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 Vitamin E and Glycerol Phenylbutyrate Together: Common Questions

Is it safe to take Vitamin E with Glycerol Phenylbutyrate?
We do not list a known interaction between Vitamin E 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 Vitamin E 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 Vitamin E 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 Vitamin E 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.
How was the Vitamin E and Glycerol Phenylbutyrate combination checked?
Interactions in our licensed database are recorded against drug classes. Glycerol Phenylbutyrate is filed under 1 classification, and Vitamin E has documented interactions with 8 drug classes — none of Glycerol Phenylbutyrate'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 Vitamin E interact with any other medications?
Yes. Vitamin E has 764 documented drug interactions in our database — Glycerol Phenylbutyrate 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 Glycerol Phenylbutyrate interact with any supplements?
Yes. Glycerol Phenylbutyrate has documented interactions with 17 supplements in our database — Vitamin E 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

Vitamin E 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 64 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Glycerol Phenylbutyrate and Vitamin E?

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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.