Drug & supplement interaction

Blond Psyllium + Methylnaltrexone

Methylnaltrexone brand name: Relistor.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Sep 20, 2026

The bottom line No known interaction

We found no known interaction between Blond Psyllium and Methylnaltrexone 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 Methylnaltrexone 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

Blond Psyllium and Methylnaltrexone

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 Methylnaltrexone and Blond Psyllium 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.

Blond Psyllium safety at a glance

Blond Psyllium overall Generally safe Generally well tolerated for most adults when taken with enough water.

Pregnancy Likely Safe When used orally and appropriately. Read the full pregnancy detail

Breastfeeding Likely Safe When used orally and appropriately. 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 Methylnaltrexone and Blond Psyllium? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

How we checked

Why No Interaction Is Listed for Methylnaltrexone

Interactions in our licensed database are recorded against drug classes, not just single drug names. Methylnaltrexone is filed under a single classification — cytochrome p450 2d6 (cyp2d6) inhibitors. Blond Psyllium has documented interactions with 7 drug classes — the most serious being carbamazepine (tegretol) (moderate), lithium (moderate) and metformin (glucophage) (moderate) — and none of Methylnaltrexone’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

Blond Psyllium Does Interact With Other Medications

Blond Psyllium has 23 moderate, 2,002 minor known drug interactions in our database — Methylnaltrexone isn’t one of them. If you take anything else, check it against the full list below.

Moderate 23 Minor 2,002 No known interaction 805 (incl. Methylnaltrexone)

Taking anything else?

Check Another of Your Medications Against Blond Psyllium

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

What to actually watch for

No Interaction Found — But Data Suggests Blond Psyllium and Methylnaltrexone 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.

Flushing Additional detail
Blond Psyllium
“Some patients can have an allergic response to blond psyllium. Allergy symptoms include allergic rhinitis, sneezing, conjunctivitis, urticarial rash, itching, flushing, and dyspnea. More serious symptoms include wheezing, facial and body swelling, chest congestion, chest and throat tightness, cough, diarrhea, hypotension, loss of consciousness, and anaphylactic shock.”

Blond Psyllium · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).
6 sources cited

2328. Suhonen R, Kantola I, Bjorksten F. Anaphylactic shock due to ingestion of psyllium laxative. Allergy 1983;38:363-5. PubMed

2329. Vaswani SK, Hamilton RG, Valentine MD, Adkinson NF. Psyllium laxative-induced anaphylaxis, asthma, and rhinitis. Allergy 1996;51:266-8. PubMed

2330. Freeman GL. Psyllium hypersensitivity. Ann Allergy 1994;73:490-2.

8079. Lantner RR, Espiritu BR, Zumerchik P, Tobin MC. Anaphylaxis following ingestion of a psyllium-containing cereal. JAMA 1990;264:2534-6. DOI

9246. Kaplan MJ. Anaphylactic reaction to "Heartwise." N Engl J Med 1990;323:1072-3. DOI

92193. Bernedo N, García M, Gastaminza G, et al. Allergy to laxative compound (Plantago ovata seed) among health care professionals. J Investig Allergol Clin Immunol 2008;18(3):181-9.
Methylnaltrexone

Listed in the ADVERSE REACTIONS section of the FDA label for Methylnaltrexone. Read the label on DailyMed ›
Bloating or gas / Stomach upset / Constipation / Stomach pain / Nausea Additional detail
Blond Psyllium
“Orally, blond psyllium can cause transient flatulence, abdominal pain, diarrhea, constipation, dyspepsia, and nausea. Starting with a low dose and slowly titrating to the desired dose can often minimize gastrointestinal side effects. There is some concern that blond psyllium can cause esophageal or bowel obstruction when consumed without adequate water or in patients with swallowing disorders.”

Blond Psyllium · Natural Medicines adverse-effect record, reported in constipation.
6 sources cited

1376. Anderson JW, Allgood LD, Lawrence A, et al. Cholesterol-lowering effects of psyllium intake adjunctive to diet therapy in men and women with hypercholesterolemia: meta-analysis of 8 controlled trials. Am J Clin Nutr 2000;71:472-9. PubMed

604. Agha FP, Nostrant TT, Fiddian-Green RG. Giant colonic bezoar: a medication bezoar due to psyllium seed husks. Am J Gastroenterol 1984;79:319-21.

8080. Schneider RP. Perdiem causes esophageal impaction and bezoars. South Med J 1989;82:1449-50. PubMed

8081. Shulman LM, Minagar A, Weiner WJ. Perdiem causing esophageal obstruction in Parkinson's disease. Neurology 1999;52:670-1. PubMed

110760. Shin S, Kim JH, Mun YH, Chung HS. Acute esophageal obstruction after ingestion of psyllium seed husk powder: A case report. World J Clin Cases 2022;10(7):2336-2340. PubMed

112998. Tominaga Y, Hirayama I, Nonaka M, Yano T, Ishii M. Intestinal obstruction caused by consuming diet food containing psyllium. Acute Med Surg 2023;10(1):e846. PubMed
Methylnaltrexone

Listed in the ADVERSE REACTIONS section of the FDA label for Methylnaltrexone. Read the label on DailyMed ›
Diarrhea Additional detail

Blond Psyllium

Recorded for Blond Psyllium in the same Natural Medicines adverse-effect record shown under Bloating or gas / Stomach upset / Constipation / Stomach pain / Nausea above.

Methylnaltrexone

Listed in the ADVERSE REACTIONS section of the FDA label for Methylnaltrexone. Read the label on DailyMed ›
Headache Additional detail
Blond Psyllium
“Orally, headache has been reported with the use of psyllium.”

Blond Psyllium · Natural Medicines adverse-effect record, reported in cluster headache.
1 source cited

1376. Anderson JW, Allgood LD, Lawrence A, et al. Cholesterol-lowering effects of psyllium intake adjunctive to diet therapy in men and women with hypercholesterolemia: meta-analysis of 8 controlled trials. Am J Clin Nutr 2000;71:472-9. PubMed
Methylnaltrexone

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

Reported for Blond Psyllium but not commonly for Methylnaltrexone: a bowel blockage, fainting, an allergic reaction and a severe allergic reaction.

Effects for Methylnaltrexone come from the ADVERSE REACTIONS section of its FDA label; effects for Blond Psyllium 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

Blond Psyllium in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Safe

When used orally and appropriately.

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 Methylnaltrexone Products Have a Food Rule — Blond Psyllium Should Not Break It

At least one FDA label for a product containing Methylnaltrexone says to take it on an empty stomach. Most supplements — Blond Psyllium included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Methylnaltrexone on its own and move Blond Psyllium 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 Methylnaltrexone 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.

o In patients with chronic non-cancer pain and OIC, take RELISTOR tablets with water on an empty stomach at least 30 minutes before the first meal of the day.

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

Overlapping uses

What Methylnaltrexone Is Prescribed For, and What Blond Psyllium Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Methylnaltrexone is a prescription medicine with approved uses on its FDA label. Blond Psyllium is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Methylnaltrexone is prescribed for: Methylnaltrexone, sold as Relistor, treats opioid-induced constipation (OIC) — constipation caused by opioid pain medications. Both Relistor tablets and Relistor injection are approved for adults with chronic non-cancer pain, including those with pain related to a prior cancer or its treatment who do not need frequent opioid dose increases. Relistor injection is also approved for adults with advanced illness or active cancer pain who require increasing opioid doses as part of palliative care.

Blond Psyllium has been studied for:

Constipation Natural Medicines rates the evidence for Blond Psyllium: Effective Read what the research shows

Blond Psyllium for constipation

Oral blond psyllium is effective as a bulk laxative for reducing constipation and for softening stools.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Methylnaltrexone on your own; if you are taking Blond Psyllium for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

Everything else you take

See Every Supplement That Interacts With Methylnaltrexone

This page covers Blond Psyllium only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Methylnaltrexone page lists 3 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Fever Bark (moderate), Iboga (moderate) and Yohimbe (moderate).

By severity: 3 moderate.

From our pharmacist’s overview on the Methylnaltrexone page

“If you take methylnaltrexone (Relistor) for opioid-induced constipation, the supplement list to know is short: three ingredients, all rated moderate, none major. Yohimbe, fever bark, and iboga are all cleared by the same liver enzyme, CYP2D6, and methylnaltrexone can slow that enzyme, letting their active compounds build up in your blood.”

Reviewed by 2 · Jul 18, 2026

Open the Methylnaltrexone interaction page

One more smart check

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

We hold 97 real supplement products containing Blond Psyllium, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Blond Psyllium. Even though Blond Psyllium itself has no known interaction with Methylnaltrexone, 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 Blond Psyllium and Methylnaltrexone 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 Blond Psyllium

Top half

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

29 days ago today

Medication Methylnaltrexone

Steady interest

#2,565 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 Blond Psyllium reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Blond Psyllium and Methylnaltrexone 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 Dr. Brian Staiger, PharmD, BCPS.

Supplement

About Blond Psyllium

What is Blond Psyllium?

Constipation relief
Diarrhea and loose stools
High cholesterol
Digestive/gut health
Blood sugar support
Feeling fuller for weight management

Blond psyllium is a soluble fiber from the seed husks of Plantago ovata, and it is one of the better-studied fiber supplements. It can help with both constipation and diarrhea and may modestly lower cholesterol and blood sugar. It is generally well tolerated when taken with plenty of water, but always start low and check with your pharmacist or doctor first.

Plantago ovata · Plantaginaceae · Seeds and seed husks · Powder, capsules, wafers, granules, and pre-mixed drink products

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

Blond Psyllium: dosing

There is no single official dose of blond psyllium for everyone, and the right amount depends on the product and what you are using it for. Drink extra water throughout the day. Take psyllium at a different time from your medications, since fiber can affect how other things are absorbed.

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

Read the full Blond Psyllium monograph & all interactions

Medication

About Methylnaltrexone

What Is Methylnaltrexone Used For?

Brand name: Relistor

Methylnaltrexone, sold as Relistor, treats opioid-induced constipation (OIC) — constipation caused by opioid pain medications. Both Relistor tablets and Relistor injection are approved for adults with chronic non-cancer pain, including those with pain related to a prior cancer or its treatment who do not need frequent opioid dose increases.

Relistor injection is also approved for adults with advanced illness or active cancer pain who require increasing opioid doses as part of palliative care.

See full Methylnaltrexone drug information

Keep checking

Other Drugs & Blond Psyllium

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

0Major

23Moderate

2,002Minor

804No known interaction

23 Moderate 2,002 Minor 804 No interaction

Moderate

23 interactions

Minor

2,002 interactions

Showing 60 of 2,002 minor interactions — see all 2,002 on the Blond Psyllium page.

No interaction 804 drugs checked — show the list

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

Showing the 60 most looked-up of 804 medications checked with no known interaction — see the full Blond Psyllium list.

See the full Blond Psyllium interactions page

See every supplement checked against Methylnaltrexone, ranked by severity

Evidence & sources

Blond Psyllium References

The 28 references that drive our Blond Psyllium 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.

McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
Covington TR, et al. Handbook of Nonprescription Drugs. 11th ed. Washington, DC: American Pharmaceutical Association, 1996.
Etman M. Effect of a bulk forming laxative on the bioavailablility of carbamazepine in man. Drug Dev Ind Pharm 1995;21:1901-6.
Perlman BB. Interaction between lithium salts and ispaghula husk. Lancet 1990;335:416.
Agha FP, Nostrant TT, Fiddian-Green RG. Giant colonic bezoar: a medication bezoar due to psyllium seed husks. Am J Gastroenterol 1984;79:319-21.
Anderson JW, Allgood LD, Lawrence A, et al. Cholesterol-lowering effects of psyllium intake adjunctive to diet therapy in men and women with hypercholesterolemia: meta-analysis of 8 controlled trials. Am J Clin Nutr 2000;71:472-9. PubMed
Suhonen R, Kantola I, Bjorksten F. Anaphylactic shock due to ingestion of psyllium laxative. Allergy 1983;38:363-5. PubMed
Vaswani SK, Hamilton RG, Valentine MD, Adkinson NF. Psyllium laxative-induced anaphylaxis, asthma, and rhinitis. Allergy 1996;51:266-8. PubMed
Freeman GL. Psyllium hypersensitivity. Ann Allergy 1994;73:490-2.
Morgan MS, Arlian LG, Vyszenski-Moher DL, et al. English plantain and psyllium: lack of cross-allergenicity by crossed immunoelectrophoresis. Ann Allergy Asthma Immunol 1995;75:351-9.
Lantner RR, Espiritu BR, Zumerchik P, Tobin MC. Anaphylaxis following ingestion of a psyllium-containing cereal. JAMA 1990;264:2534-6. DOI
Schneider RP. Perdiem causes esophageal impaction and bezoars. South Med J 1989;82:1449-50. PubMed
Shulman LM, Minagar A, Weiner WJ. Perdiem causing esophageal obstruction in Parkinson's disease. Neurology 1999;52:670-1. PubMed
James JM, Cooke SK, Barnett A, Sampson HA. Anaphylactic reactions to a psyllium-containing cereal. J Allergy Clin Immunol 1991;88:402-8.. PubMed
Kaplan MJ. Anaphylactic reaction to "Heartwise." N Engl J Med 1990;323:1072-3. DOI
Schaller DR. Anaphylactic reaction to "Heartwise." N Engl J Med 1990;323:1073. DOI
Nordstrom M, Melander A, Robertsson E, Steen B. Influence of wheat bran and of a bulk-forming ispaghula cathartic on the bioavailability of digoxin in geriatric in-patients. Drug Nutr Interact 1987;5:67-9..
Robinson DS, Benjamin DM, McCormack JJ. Interaction of warfarin and nonsystemic gastrointestinal drugs. Clin Pharmacol Ther 1971;12:491-5. PubMed
Garcia JJ, Fernandez N, Diez MJ, et al. Influence of two dietary fibers in the oral bioavailability and other pharmacokinetic parameters of ethinyloestradiol. Contraception 2000;62:253-7. PubMed
Bernedo N, García M, Gastaminza G, et al. Allergy to laxative compound (Plantago ovata seed) among health care professionals. J Investig Allergol Clin Immunol 2008;18(3):181-9.
Fernandez N, Lopez C, Díez R, et al. Drug interactions with the dietary fiber Plantago ovata husk. Expert Opin Drug Metab Toxicol 2012;8(11):1377-86.
Semen plantaginis in: WHO Monographs on Selected Medicinal Plants, volume 1. World Health Organization, Geneva, 1999. Available at http://apps.who.int/medicinedocs/en/d/Js2200e/. Accessed November 26, 1026.
Diez R, Garcia JJ, Diez MJ, Sierra M, Sahagun AM, Fernandez N. Influence of Plantago ovata husk (dietary fiber) on the bioavailability and other pharmacokinetic parameters of metformin in diabetic rabbits. BMC Complement Altern Med. 2017 Jun 7;17(1):298. PubMed
Chiu AC, Sherman SI. Effects of pharmacological fiber supplements on levothyroxine absorption. Thyroid. 1998;8(8):667-71. PubMed
Merrick C, Madden CA, Capurso NA. A Case of Blunted Orally Disintegrating Olanzapine Effect Due to Coadministered Psyllium. J Clin Psychiatry 2021;82(2):20cr13633. PubMed
Shin S, Kim JH, Mun YH, Chung HS. Acute esophageal obstruction after ingestion of psyllium seed husk powder: A case report. World J Clin Cases 2022;10(7):2336-2340. PubMed
Tominaga Y, Hirayama I, Nonaka M, Yano T, Ishii M. Intestinal obstruction caused by consuming diet food containing psyllium. Acute Med Surg 2023;10(1):e846. 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 Blond Psyllium and Methylnaltrexone Together: Common Questions

Is it safe to take Blond Psyllium with Methylnaltrexone?

We do not list a known interaction between Blond Psyllium and Methylnaltrexone. 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 Blond Psyllium and Methylnaltrexone have any of the same side effects?

Yes — our sources link each of them separately to 8 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 Blond Psyllium and Methylnaltrexone at the same time of day?

At least one FDA label for a product containing Methylnaltrexone 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 Methylnaltrexone on its own and move Blond Psyllium 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.

Are Blond Psyllium and Methylnaltrexone used for the same thing?

They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Blond Psyllium in each. That is a conversation for your prescriber, especially if Methylnaltrexone is being adjusted to a target.

How was the Blond Psyllium and Methylnaltrexone combination checked?

Interactions in our licensed database are recorded against drug classes. Methylnaltrexone is filed under 1 classification, and Blond Psyllium has documented interactions with 7 drug classes — none of Methylnaltrexone'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 Blond Psyllium interact with any other medications?

Yes. Blond Psyllium has 2,025 documented drug interactions in our database — Methylnaltrexone 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 Methylnaltrexone interact with any supplements?

Yes. Methylnaltrexone has documented interactions with 3 supplements in our database — Blond Psyllium is not one of them. The Methylnaltrexone 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

Blond Psyllium monograph Uses, safety profile, and every drug interaction in one place Methylnaltrexone drug information The full plain-English guide to this medication Methylnaltrexone supplement interactions Every supplement checked against Methylnaltrexone, 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 28 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Methylnaltrexone and Blond Psyllium?

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.