Drug & supplement interaction

Casein Protein + Phendimetrazine

Phendimetrazine brand names: Plegine, Metra, Weightrol.

No Known Interaction
The bottom line No known interaction

We found no known interaction between Casein Protein and Phendimetrazine 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

Casein Protein and Phendimetrazine

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 Phendimetrazine and Casein Protein 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 Casein Protein at all — not against Phendimetrazine, 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.

Casein Protein safety at a glance

Casein Protein overall Generally safe Generally safe for healthy people who tolerate dairy when used as a food/protein source.
Pregnancy Use caution Casein as part of a normal diet is fine, but talk to your doctor before using concentrated protein supplements.
Breastfeeding Use caution Dietary casein is fine, but discuss supplement powders with your doctor first.

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

Still wondering about combining Phendimetrazine and Casein Protein? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Casein Protein and Phendimetrazine 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.

  • Constipation / Diarrhea Additional detail

    Casein Protein

    “Orally, casein protein is well tolerated in adults and seems to be well tolerated in infants. Side effects reported in clinical trials did not occur more commonly than placebo. Some of these reported side effects include diarrhea, constipation, vomiting, and delayed gastric emptying. In preterm infants, casein protein has been associated with an increased risk for metabolic acidosis.”

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

    6 sources cited
    1. 85932. Claessens, M., van Baak, M. A., Monsheimer, S., and Saris, W. H. The effect of a low-fat, high-protein or high-carbohydrate ad libitum diet on weight loss maintenance and metabolic risk factors. Int J Obes.(Lond) 2009;33(3):296-304. PubMed
    2. 91251. Tarnopolsky MA, Parise G, Yardley NJ, et al. Creatine-dextrose and protein-dextrose induce similar strength gains during training. Med Sci Sports Exerc 2001;33(12):2044-52. PubMed
    3. 91266. Kearns PJ, Young H, Garcia G, et al. Accelerated improvement of alcoholic liver disease with enteral nutrition. Gastroenterology 1992;102(1):200-5. PubMed
    4. 91286. Pal S, Radavelli-Bagatini S, Hagger M, Ellis V. Comparative effects of whey and casein proteins on satiety in overweight and obese individuals: a randomized controlled trail. Eur J Clin Nutr 2014;68(9):980-6.
    5. 91294. Anderson JW, Fuller J, Patterson K, et al. Soy compared to casein meal replacement shakes with energy-restricted diets for obese women: randomized controlled trial. Metabolism 2007;56(2):280-8. PubMed
    6. 91299. Geerts BF, van Dongen MG, Flameling B, et al. Hydrolyzed casein decreases posprandial glucose concentrations in T2DM patients irrespective of leucine content. J Diet Suppl 2011;8(3):280-92.

    “Orally, casein protein-based enteral nutrition has been reported to cause diarrhea and vomiting in adults. Casein protein-predominant formula has been reported to cause constipation in infants. Casein protein-based formula can delay gastric emptying when compared with whey protein-based formula.”

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

    4 sources cited
    1. 91640. Viall C, Porcelli K, Teran JC, et al. A double-blind clinical trial comparing the gastrointestinal side effects of two enteral feeding formulas. JPEN J Parenter Enteral Nutr 1990;14(3):265-9. PubMed
    2. 91667. Gunn TR, Stunzer D. A comparative trial of casein or whey-predominant formulae in healthy infants. N Z Med J 1986;99(813):843-6.
    3. 86084. Brun, A. C., Stordal, K., Johannesdottir, G. B., Bentsen, B. S., and Medhus, A. W. The effect of protein composition in liquid meals on gastric emptying rate in children with cerebral palsy. Clin.Nutr 2012;31(1):108-112. PubMed
    4. 86103. Savage, K., Kritas, S., Schwarzer, A., Davidson, G., and Omari, T. Whey- vs casein-based enteral formula and gastrointestinal function in children with cerebral palsy. JPEN J Parenter.Enteral Nutr 2012;36(1 Suppl):118S-123S. PubMed

    Phendimetrazine

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

Reported for Casein Protein but not commonly for Phendimetrazine: stomach upset, shortness of breath, an allergic reaction and a severe allergic reaction.

Effects for Phendimetrazine come from the ADVERSE REACTIONS section of its FDA label; effects for Casein Protein 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.

Overlapping uses

What Phendimetrazine Is Prescribed For, and What Casein Protein Has Been Studied For

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

Phendimetrazine is prescribed for: Phendimetrazine tartrate is used to help manage exogenous obesity (excess body weight from outside causes like diet and lifestyle) as a short-term addition to a calorie-restricted diet. It is intended for adults with a BMI of 30 or higher, or a BMI of 27 or higher when other risk factors — such as high blood pressure, diabetes, or high cholesterol — are also present. It is approved for use as monotherapy only, meaning it must not be combined with other weight-loss drugs or stimulants. Both the tablet form and the extended-release capsule form are approved for this purpose.

Read the rest of what Phendimetrazine is prescribed for

This medication is meant to be used for only a few weeks as part of a broader weight-management plan.

Casein Protein has been studied for:

  • Obesity studied, not established Casein Protein has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Casein Protein for obesity

    Most clinical research shows that supplementation with casein protein does not reduce body weight or appetite when compared to control in overweight and obese patients. However, some clinical research in overweight patients shows that consumption of a liquid snack containing 30 grams of casein or whey protein extends the duration of satiety compared with a carbohydrate snack.

    7 sources cited
    1. 86011. Pal, S., Ellis, V., and Dhaliwal, S. Effects of whey protein isolate on body composition, lipids, insulin and glucose in overweight and obese individuals. Br J Nutr 2010;104(5):716-723. PubMed
    2. 86105. Lorenzen, J., Frederiksen, R., Hoppe, C., Hvid, R., and Astrup, A. The effect of milk proteins on appetite regulation and diet-induced thermogenesis. Eur.J Clin.Nutr 2012;66(5):622-627. PubMed
    3. 91286. Pal S, Radavelli-Bagatini S, Hagger M, Ellis V. Comparative effects of whey and casein proteins on satiety in overweight and obese individuals: a randomized controlled trail. Eur J Clin Nutr 2014;68(9):980-6.
    4. 91284. Marsset-Baglieri A, Fromentin G, Airinei G, et al. Milk protein fractions moderately extend the duration of satiety compared with carbohydrates independently of their digestive kinetics in overweight subjects. Br J Nutr 2014;112(4):557-64. PubMed
    5. 85932. Claessens, M., van Baak, M. A., Monsheimer, S., and Saris, W. H. The effect of a low-fat, high-protein or high-carbohydrate ad libitum diet on weight loss maintenance and metabolic risk factors. Int J Obes.(Lond) 2009;33(3):296-304. PubMed
    6. 91272. Bendtsen LQ, Lorenzen JK, Gomes S, et al. Effects of hydrolysed casein, intact casein and intact whey protein on energy expenditure and appetite regulation: a randomised, controlled, cross-over stuy. Br J Nutr 2014;112(8):1412-22.
    7. 91294. Anderson JW, Fuller J, Patterson K, et al. Soy compared to casein meal replacement shakes with energy-restricted diets for obese women: randomized controlled trial. Metabolism 2007;56(2):280-8. PubMed
  • Diabetes studied, not established Casein Protein has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Casein Protein for diabetes

    A clinical study in men with diabetes shows that drinking a beverage containing carbohydrates and casein protein 0.3 g/kg as a single dose increases plasma insulin levels and tends to lower levels of plasma glucose when compared with placebo. However, there was no difference between beverages containing intact casein protein or casein peptides.

    2 sources cited
    1. 91276. Manders RJ, Hansen D, Zorenc AH, et al. Protein co-ingestion strongly increases postprandial insulin secretion in type 2 diabetes patients. J Med Food 2014;17(7):758-63. PubMed
    2. 91299. Geerts BF, van Dongen MG, Flameling B, et al. Hydrolyzed casein decreases posprandial glucose concentrations in T2DM patients irrespective of leucine content. J Diet Suppl 2011;8(3):280-92.

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 Phendimetrazine on your own; if you are taking Casein Protein 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 Phendimetrazine

This page covers Casein Protein only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phendimetrazine 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 Phendimetrazine page

“Of the 17 supplements on file for phendimetrazine, an appetite-suppressant stimulant prescribed short term for weight loss, activated charcoal is the one that demands real caution. Charcoal binds medications in the gut and can sharply cut how much of a drug your body absorbs, leaving you with less appetite control than your prescriptio…”

Reviewed by 2 · Jul 18, 2026

Open the Phendimetrazine interaction page

One more smart check

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

We hold 246 real supplement products containing Casein Protein, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Casein Protein. Even though Casein Protein itself has no known interaction with Phendimetrazine, 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 Casein Protein and Phendimetrazine 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 Casein Protein
Top half

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

29 days ago today
Medication Phendimetrazine
Top 25%

#354 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 Casein Protein reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Casein Protein and Phendimetrazine 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 Casein Protein

What is Casein Protein?

  • Muscle building and recovery
  • Slow-release protein before sleep
  • Meal replacement and weight management
  • Increasing daily protein intake
  • Supporting athletic training

Casein is a slow-digesting protein from milk that supplies all the essential amino acids and is popular for muscle recovery, especially overnight. It is generally safe for most people who tolerate dairy, but those with a milk allergy should avoid it. As with any supplement, check with your pharmacist or doctor, especially if you have kidney problems.

Milk-derived protein (from cow's milk) · Powders, ready-to-drink shakes, protein bars; also as micellar casein or calcium caseinate

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

Casein Protein: dosing

There is no official standardized dose of casein protein. The right amount depends on your overall diet, body size, activity level, and goals.Most casein supplements provide about 20 to 30 grams of protein per serving, but you should follow the directions on the product label. Many people take it once a day, often in the evening or before bed because of its slow digestion.Remember that your total daily protein from all foods matters most.

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

Read the full Casein Protein monograph & all interactions
Medication

About Phendimetrazine

What Is Phendimetrazine Used For?

Brand names: Plegine, Metra, Weightrol

Phendimetrazine tartrate is used to help manage exogenous obesity (excess body weight from outside causes like diet and lifestyle) as a short-term addition to a calorie-restricted diet. It is intended for adults with a BMI of 30 or higher, or a BMI of 27 or higher when other risk factors — such as high blood pressure, diabetes, or high cholesterol — are also present.

It is approved for use as monotherapy only, meaning it must not be combined with other weight-loss drugs or stimulants. Both the tablet form and the extended-release capsule form are approved for this purpose. This medication is meant to be used for only a few weeks as part of a broader weight-management plan.

See full Phendimetrazine drug information
Keep checking

Other Drugs & Casein Protein

Browse every other medication we’ve checked against Casein Protein — 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
No interaction 2,829 drugs checked — show the list
Evidence & sources

Casein Protein References

The 61 references that drive our Casein Protein 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. Marchesini G, Dioguardi FS, Bianchi GP, et al. Long-term oral branched-chain amino acid treatment in chronic hepatic encephalopathy. A randomized double-blind casein-controlled trial. The Italian Multicenter Study Group. J Hepatol 1990;11:92-101. PubMed
  2. Potter SM, Baum JA, Teng H, et al. Soy protein and isoflavones: their effects on blood lipids and bone density in postmenopausal women. Am J Clin Nutr 1998;68:1375S-9S. PubMed
  3. Nilausen K, Meinertz H. Variable lipemic response to dietary soy protein in healthy, normolipemic men. Am J Clin Nutr 1998;68:1380S-4S. PubMed
  4. Teixeira SR, Potter SM, Weigel R, et al. Effects of feeding 4 levels of soy protein for 3 and 6 wk on blood lipids and apolipoproteins in moderately hypercholesterolemic men. Am J Clin Nutr 2000;71:1077-84. PubMed
  5. Tonstad S, Smerud K, Hoie L. A comparison of the effects of 2 doses of soy protein or casein on serum lipids, serum lipoproteins, and plasma total homocysteine in hypercholesterolemic subjects. Am J Clin Nutr 2002;76:78-84. PubMed
  6. Teede HJ, Dalais FS, Kotsopoulos D, et al. Dietary soy has both beneficial and potentially adverse cardiovascular effects: a placebo-controlled study in men and postmenopausal women. J Clin Endocrinol Metab 2001;86:3053-60. DOI
  7. Nilausen, K. and Meinertz, H. Lipoprotein(a) and dietary proteins: casein lowers lipoprotein(a) concentrations as compared with soy protein. Am.J.Clin.Nutr. 1999;69(3):419-425. PubMed
  8. Meinertz, H., Nilausen, K., and Hilden, J. Alcohol-extracted, but not intact, dietary soy protein lowers lipoprotein(a) markedly. Arterioscler.Thromb.Vasc.Biol. 2-1-2002;22(2):312-316. PubMed
  9. Dalais, F. S., Ebeling, P. R., Kotsopoulos, D., McGrath, B. P., and Teede, H. J. The effects of soy protein containing isoflavones on lipids and indices of bone resorption in postmenopausal women. Clin Endocrinol.(Oxf) 2003;58(6):704-709. PubMed
  10. Cuevas, A. M., Irribarra, V. L., Castillo, O. A., Yanez, M. D., and Germain, A. M. Isolated soy protein improves endothelial function in postmenopausal hypercholesterolemic women. Eur.J Clin.Nutr. 2003;57(8):889-894. PubMed
  11. Hermansen, K., Hansen, B., Jacobsen, R., Clausen, P., Dalgaard, M., Dinesen, B., Holst, J. J., Pedersen, E., and Astrup, A. Effects of soy supplementation on blood lipids and arterial function in hypercholesterolaemic subjects. Eur.J Clin.Nutr. 2005;59(7 PubMed
  12. Meinertz, H., Nilausen, K., and Faergeman, O. Soy protein and casein in cholesterol-enriched diets: effects on plasma lipoproteins in normolipidemic subjects. Am J Clin Nutr 1989;50(4):786-793. PubMed
  13. van Raaij, J. M., Katan, M. B., Hautvast, J. G., and Hermus, R. J. Effects of casein versus soy protein diets on serum cholesterol and lipoproteins in young healthy volunteers. Am J Clin Nutr 1981;34(7):1261-1271. PubMed
  14. van Raaij, J. M., Katan, M. B., West, C. E., and Hautvast, J. G. Influence of diets containing casein, soy isolate, and soy concentrate on serum cholesterol and lipoproteins in middle-aged volunteers. Am J Clin Nutr 1982;35(5):925-934. PubMed
  15. Gooderham, M. H., Adlercreutz, H., Ojala, S. T., Wahala, K., and Holub, B. J. A soy protein isolate rich in genistein and daidzein and its effects on plasma isoflavone concentrations, platelet aggregation, blood lipids and fatty acid composition of plasm

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 Casein Protein and Phendimetrazine Together: Common Questions

Is it safe to take Casein Protein with Phendimetrazine?
We do not list a known interaction between Casein Protein and Phendimetrazine. 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 Casein Protein and Phendimetrazine 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.
Are Casein Protein and Phendimetrazine 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 Casein Protein in each. That is a conversation for your prescriber, especially if Phendimetrazine is being adjusted to a target.
Does Phendimetrazine interact with any supplements?
Yes. Phendimetrazine has documented interactions with 17 supplements in our database — Casein Protein is not one of them. The Phendimetrazine interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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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.