Drug & supplement interaction

Casein Protein + Sildenafil

Sildenafil brand name: Revatio.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Sep 13, 2026

The bottom line No known interaction

We found no known interaction between Casein Protein and Sildenafil 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 Sildenafil

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 Sildenafil 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 Sildenafil, 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 Sildenafil and Casein Protein? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

What to actually watch for

No Interaction Found — But Data Suggests Casein Protein and Sildenafil May Share a Side Effect

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 upset Additional detail
Casein Protein
“Rarely, allergic reaction to casein protein has been reported. Symptoms include skin reactions, difficulty breathing, gastrointestinal distress, and anaphylaxis. At one time, casein protein was thought to be the major allergenic and antigenic protein in cow's milk. However, it is now known that no specific protein or peptide in cow's milk is primarily responsible for cow's milk allergy;”

Casein Protein · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).
3 sources cited

91629. Lam HY, van Hoffen E, Michelsen A, et al. Cow's milk allergy in adults is rare but severe: Both casein and whey proteins are involved. Clin Exp Allergy 2008;38(6):995-1002. PubMed

91627. Docena GH, Fernandez R, Chirdo FG, Fossati CA. Identification of casein as the major allergenic and antigenic protein of cow's milk. Allergy 1996;51(6):412-6. PubMed

91628. Wal JM. Bovine milk allergenicity. Ann Allergy Asthma Immunol 2004;93(5 Suppl 3):S2-11. PubMed
Sildenafil

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

Reported for Casein Protein but not commonly for Sildenafil: shortness of breath, an allergic reaction, constipation and a severe allergic reaction.

Effects for Sildenafil 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 Sildenafil 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. Sildenafil 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.

Sildenafil is prescribed for: Sildenafil treats two distinct conditions depending on the product. Viagra (tablet) and Vybrique (dissolving oral film) are approved for erectile dysfunction (ED) — difficulty getting or keeping an erection. Generic sildenafil tablets and oral film are also approved for ED. Revatio and several generic sildenafil products (tablets, oral suspension, and injection) are used for pulmonary arterial hypertension (PAH) — high blood pressure in the arteries of the lungs — in adults to improve exercise ability and slow the disease from getting worse.

Read the rest of what Sildenafil is prescribed for

Revatio oral suspension and injection are also approved for PAH in children ages 1 to 17.

Casein Protein has been studied for:

Hypertension 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 hypertension
The effects of casein protein on blood pressure are unclear. Clinical research in overweight and obese adults shows that taking casein protein 54 grams daily for 12 weeks reduces diastolic blood pressure, but not systolic blood pressure, by 3% when compared with a control diet.
2 sources cited

85981. Pal, S. and Ellis, V. The chronic effects of whey proteins on blood pressure, vascular function, and inflammatory markers in overweight individuals. Obesity.(Silver.Spring) 2010;18(7):1354-1359. PubMed

91280. Figueroa A, Wong A, Kinsey A, et al. Effects of milk proteins and combined exercise training on aortic hemodynamics and arterial stiffness in young obese women with high blood pressure. Am J Hypertens 2014;27(3):338-44. PubMed

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 Sildenafil 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.

From our Q&A

Questions About Casein Protein or Sildenafil

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Casein Protein or Sildenafil, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Sildenafil

This page covers Casein Protein only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Sildenafil page lists 160 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Mistletoe (major), Grapefruit (major), Hawthorn (major) and St. John's Wort (major).

By severity: 5 major · 114 moderate · 41 minor.

From our pharmacist’s overview on the Sildenafil page

“Sildenafil relaxes blood vessels, whether prescribed as Revatio for pulmonary hypertension or as Viagra, and that blood-pressure-lowering action makes this list one to treat with genuine care. Of the 160 supplement and herbal ingredients on file, five carry a major rating, and those deserve understanding first.”

Reviewed by 2 · Jul 18, 2026

Open the Sildenafil 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 Sildenafil, 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 Sildenafil 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

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

29 days ago today

Medication Sildenafil

Top 25%

#574 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 Sildenafil 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 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 Sildenafil

What Is Sildenafil Used For?

Brand name: Revatio

Sildenafil treats two distinct conditions depending on the product. Viagra (tablet) and Vybrique (dissolving oral film) are approved for erectile dysfunction (ED) — difficulty getting or keeping an erection. Generic sildenafil tablets and oral film are also approved for ED.

Revatio and several generic sildenafil products (tablets, oral suspension, and injection) are used for pulmonary arterial hypertension (PAH) — high blood pressure in the arteries of the lungs — in adults to improve exercise ability and slow the disease from getting worse. Revatio oral suspension and injection are also approved for PAH in children ages 1 to 17.

Most-Reported Side Effects for Sildenafil

From FAERS, the FDA’s public side-effect reporting system (126,564 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dyspnea 13,327 reports

Headache 10,220 reports

Diarrhea 7,049 reports

Nausea 6,489 reports

Fatigue 6,390 reports

See full Sildenafil 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

2,829 No interaction

No interaction 2,829 drugs checked — show the list

We also checked Casein Protein 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 Casein Protein list.

See the full Casein Protein interactions page

See every supplement checked against Sildenafil, ranked by severity

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.

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
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
Nilausen K, Meinertz H. Variable lipemic response to dietary soy protein in healthy, normolipemic men. Am J Clin Nutr 1998;68:1380S-4S. PubMed
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
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
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
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
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
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
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
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
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
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
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
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
Baum, J. A., Teng, H., Erdman, J. W., Jr., Weigel, R. M., Klein, B. P., Persky, V. W., Freels, S., Surya, P., Bakhit, R. M., Ramos, E., Shay, N. F., and Potter, S. M. Long-term intake of soy protein improves blood lipid profiles and increases mononuclear
Willoughby, D. S., Stout, J. R., and Wilborn, C. D. Effects of resistance training and protein plus amino acid supplementation on muscle anabolism, mass, and strength. Amino.Acids 2007;32(4):467-477. PubMed
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
Hoffman, J. R., Ratamess, N. A., Tranchina, C. P., Rashti, S. L., Kang, J., and Faigenbaum, A. D. Effect of a proprietary protein supplement on recovery indices following resistance exercise in strength/power athletes. Amino.Acids 2010;38(3):771-778. PubMed
Pal, S. and Ellis, V. The chronic effects of whey proteins on blood pressure, vascular function, and inflammatory markers in overweight individuals. Obesity.(Silver.Spring) 2010;18(7):1354-1359. PubMed
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
Laviolette, L., Lands, L. C., Dauletbaev, N., Saey, D., Milot, J., Provencher, S., LeBlanc, P., and Maltais, F. Combined effect of dietary supplementation with pressurized whey and exercise training in chronic obstructive pulmonary disease: a randomized,
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
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
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
Khoshoo, V., Zembo, M., King, A., Dhar, M., Reifen, R., and Pencharz, P. Incidence of gastroesophageal reflux with whey- and casein-based formulas in infants and in children with severe neurological impairment. J Pediatr Gastroenterol.Nutr 1996;22(1):48- DOI
Cepero, M. Influence of ingesting casein protein and whey carbohydrate beverages on recovery and performance of an endurance cycling test. Journal of Human Sport & Exercise 2010;5(2):158.
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
Ormsbee MJ, Mandler WK, Thomas DD, et al. The effects of six weeks of supplementation with multi-ingredient performance supplements and resistance training on anabolic hormones, body composition, strength, and power in resistance-trained men. J Int Soc Sp PubMed
Wilborn CD, Taylor LW, Outlaw J, et al. The effects of pre- and post-exercise whey vs. casein protein consumption on body composition and performance measures in collegiate female athletes. J Sports Sci Med 2013;12(1):74-9. DOI
Hoffman JR, Ratamess NA, Tranchina CP, et al. Effect of protein-supplement timing on strength, power, and body-composition changes in resistance-trained men. Int J Sport Nutr Exerc Metab 2009;19(2):172-85. PubMed
Engelen MP, Rutten EP, De Castro CL, et al. Casein protein results in higher prandial and exercise induced whole body protein anabolism than whey protein in chronic obstructive pulmonary disease. Metabolism 2012;61(9):1289-300. PubMed
Kearns PJ, Young H, Garcia G, et al. Accelerated improvement of alcoholic liver disease with enteral nutrition. Gastroenterology 1992;102(1):200-5. PubMed
Christie ML, Sack DM, Pomposelli J, Horst D. Enriched branched-chain amino acid formula versus a casein-based supplement in the treatment of cirrhosis. JPEN J Parenter Enteral Nutr 1985;9(6):671-8. PubMed
Hirsch S, Bunout D, de la Maza P, et al. Controlled trial on nutrition supplementation in outpatients with symptomatic alcoholic cirrhosis. JPEN Parenter Enteral Nutr 1993;17(2):119-24. PubMed
Boulhosa RS, Oliveira LP, Jesus RP, et al. The impact of nutritional supplementation on quality of life in patients infected with hepatitis C virus. J Hum Nutr Diet 2013;26 Suppl 1:7-15.
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.
Wang MF, Yamamoto S, Chung HM, et al. Antihypercholesterolemic effect of undigested fraction of soybean protein in young female volunteers. J Nutr Sci Vitaminol (Tokyo) 1995;41(2):187-95. PubMed
Shige H, Ishikawa T, Higashi K, et al. Effects of soy protein isolate (SPI) and casein on the postprandial lipemia in normolipidemic men. J Nutr Sci Vitaminol (Tokyo) 1998;44(1):113-27. PubMed
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
Jenkins DJ, Srichaikul K, Wong JM, et al. Supplemental barley protein and casein similarly affect serum lipids in hypercholesterolemic women and men. J Nutr 2010;140(9):1633-7. PubMed
Figueroa A, Wong A, Kinsey A, et al. Effects of milk proteins and combined exercise training on aortic hemodynamics and arterial stiffness in young obese women with high blood pressure. Am J Hypertens 2014;27(3):338-44. PubMed
Weisse K, Brandsch C, Zernsdorf B, et al. Lupin protein compared to casein lowers the LDL cholesterol:HDL cholesterol-ratio of hypercholesterolemic adults. Eur J Nutr 2010;49(2):65-71.
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
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.
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
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.
Docena GH, Fernandez R, Chirdo FG, Fossati CA. Identification of casein as the major allergenic and antigenic protein of cow's milk. Allergy 1996;51(6):412-6. PubMed
Wal JM. Bovine milk allergenicity. Ann Allergy Asthma Immunol 2004;93(5 Suppl 3):S2-11. PubMed
Lam HY, van Hoffen E, Michelsen A, et al. Cow's milk allergy in adults is rare but severe: Both casein and whey proteins are involved. Clin Exp Allergy 2008;38(6):995-1002. PubMed
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
Lollo PC, Amaya-Farfan J, de Carvalho-Silva LB. Physiological and physical effects of different milk protein supplements in elite soccer players. J Hum Kinet 2011;30:49-57. PubMed
Taitz LS, Scholey E. Are babies more satisfied by casein based formulas? Arch Dis Child 1989;64(4):619-21. PubMed
Rajah R, Pettifor JM, Noormohamed M, et al. The effect of feeding four different formulae on stool weights in prolonged dehydrating infantile gastroenteritis. J Pediatr Gastroenterol Nutr 1988;7(2):203-7. DOI
Cooper PA, Rothberg AD, Davies VA, Argent AC. Comparative growth and biochemical response of very low birthweight infants fed own mother's milk, a premature infant formula, or one of two standard formulas. J Pediatr Gastroenterol Nutr 1985;4(5):786-94. DOI
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.
Harrison GG, Graver EJ, Vargas M, et al. Growth and adiposity of term infants fed whey-predominant or casein-predominant formulas or human milk. J Pediatr Gastroenterol Nutr 1987;6(5):739-47. DOI
Kashyap S, Okamoto E, Kanaya S, et al. Protein quality in feeding low birth weight infants: a comparison of whey-predominant versus casein-predominant formulas. Pediatrics 1987;79(5):748-55. DOI
Bernbaum JC, Sasanow SR, Churella HR, Daft A. Growth and metabolic response of premature infants fed whey- or casein-dominant formulas after hospital discharge. J Pediatr 1989;115(4):652-6. PubMed
Fok TF, So LY, Lee NN, et al. Late metabolic acidosis and poor weight gain in moderately pre-term babies fed with a casein-predominant formula: a continuing need for caution. Ann Trop Paediatr 1989;9(4):243-7. PubMed
Ormsbee MJ, Saracino PG, Morrissey MC, Donaldson J, Rentería LI, McKune AJ. Pre-sleep protein supplementation after an acute bout of evening resistance exercise does not improve next day performance or recovery in resistance trained men. J Int Soc Sports 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 Casein Protein and Sildenafil Together: Common Questions

Is it safe to take Casein Protein with Sildenafil?

We do not list a known interaction between Casein Protein and Sildenafil. 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 Sildenafil have any of the same side effects?

Yes — our sources link each of them separately to one 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 Sildenafil 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 Sildenafil is being adjusted to a target.

Does Sildenafil interact with any supplements?

Yes. Sildenafil has documented interactions with 160 supplements in our database — Casein Protein is not one of them. The Sildenafil 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

Casein Protein monograph Uses, safety profile, and every drug interaction in one place Sildenafil drug information The full plain-English guide to this medication Sildenafil supplement interactions Every supplement checked against Sildenafil, 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 61 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

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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.