Which supplement causes water retention and what you can do about it

October 20, 2025 •

4 min read

According to the International Society of Sports Nutrition, a creatine loading phase is often responsible for short-term water weight gain as muscles temporarily retain up to a liter of water. When asking "what supplement causes water retention?" creatine is the most common and scientifically-backed answer, but other supplements and ingredients can also contribute to fluid buildup, causing discomfort and a puffy appearance.

Quick Summary

Several dietary supplements can cause water retention, with creatine being the most notable due to its osmotic effect on muscle cells. Protein powders, particularly those containing lactose or artificial sweeteners, can also cause bloating and fluid retention. Proper dosage, adequate hydration, and managing other dietary factors like sodium are key to controlling this common side effect.

Key Points

Creatine's osmotic effect: Creatine is the main supplement that causes intracellular water retention, drawing fluid into muscle cells to aid performance.
Temporary water weight: The weight gain from creatine is usually temporary, most noticeable during a loading phase, and subsides within a few weeks.
Protein powder's digestive issues: Many protein powders, especially whey concentrate, can cause bloating due to lactose content or hard-to-digest artificial sweeteners.
Pre-workout's multiple culprits: Multi-ingredient pre-workouts can contain several components like creatine, caffeine, and sodium that may individually or collectively lead to fluid retention or digestive bloating.
Hydration is key: Counterintuitively, increasing water intake is one of the most effective strategies to help your body regulate fluid balance and reduce water retention.
Sodium and potassium balance: An imbalance of electrolytes, often worsened by high sodium intake, can cause water retention; increasing potassium-rich foods can help.
Dosage and ingredients matter: Choosing lower doses, skipping loading phases, or selecting supplements without problematic ingredients like sugar alcohols can minimize side effects.

Creatine: The Primary Culprit for Water Retention

Of all fitness and sports supplements, creatine is the most commonly associated with causing water retention, and for good reason—it's part of its fundamental mechanism. Creatine is an osmotically active substance, meaning it attracts and pulls water into the body's cells, particularly muscle cells.

During a typical "loading phase"—where users take a higher dose (e.g., 20 grams per day) for 5–7 days to saturate muscle stores quickly—this effect is most pronounced. While this can cause a temporary 1–2% increase in body weight from intracellular fluid, it's not a cause for concern and is often beneficial for athletic performance. The water is stored inside the muscle, which supports energy production and can stimulate muscle growth.

Intracellular, Not Subcutaneous: It's crucial to understand that creatine's water retention is primarily intracellular (inside muscle cells), not subcutaneous (under the skin). This prevents the soft, puffy look often associated with unhealthy water retention.
Temporary Effect: The initial water weight gain during the loading phase typically resolves within a few weeks as the body's fluid balance adjusts.
Dosage Matters: Those who skip the loading phase and start with a lower, daily maintenance dose (e.g., 3–5 grams) often experience less noticeable water retention.

Protein Powders and Digestive-Related Bloating

While protein powder itself doesn't cause true physiological water retention like creatine, certain ingredients can lead to gastrointestinal bloating, which many people perceive as fluid buildup. This digestive discomfort can mimic the puffy feeling of water retention.

Common causes of protein powder bloating

Lactose Sensitivity: Many people have some degree of lactose intolerance, and since whey and casein protein powders are dairy-based, they can trigger bloating, gas, and discomfort. Whey protein concentrate is more likely to cause issues than the more filtered whey protein isolate.
Artificial Sweeteners: Many flavored protein supplements contain sugar alcohols (e.g., sorbitol, xylitol) and other artificial sweeteners to enhance taste without adding calories. These can be poorly digested and fermented by gut bacteria, leading to gas and bloating.
Dietary Fiber and Thickeners: Some products use added fiber (like inulin) or gums and thickeners (like xanthan gum) that can be difficult to digest for some individuals, causing stomach upset and bloating.
Overconsumption: Drinking a large quantity of a protein shake in one sitting can overwhelm the digestive system, slowing gut motility and contributing to gas and bloating.

Pre-Workout Formulas and Other Ingredients

Many pre-workout supplements are multi-ingredient formulas that can contain creatine and other components that lead to fluid changes or digestive issues.

Creatine: As mentioned, creatine is a common ingredient in pre-workouts and can be a direct cause of temporary water retention.
Caffeine: The high doses of caffeine found in many pre-workouts can cause digestive upset and may increase stomach acid, potentially leading to bloating in sensitive individuals.
Sodium: Some formulas contain sodium to help with electrolyte balance, but a high intake of sodium can directly lead to fluid retention as the body holds onto water to balance its electrolyte levels.
Beta-Alanine: This amino acid is known for causing paresthesia (a tingling sensation), but in high doses, it can sometimes contribute to gastrointestinal discomfort.

Electrolyte Imbalance

An imbalance of electrolytes, particularly sodium and potassium, is a major driver of water retention. While some supplements like certain pre-workouts can contribute to this, other factors like diet also play a significant role. Potassium works to balance sodium and flush excess fluid, so a deficiency can exacerbate the issue. Interestingly, magnesium supplements, particularly magnesium citrate, are often used to reduce fluid retention related to premenstrual symptoms.

How to Manage Supplement-Related Water Retention

If you experience unwanted fluid retention from supplements, there are several practical steps you can take:

Stay Hydrated: It may seem counterintuitive, but drinking plenty of water helps your body regulate its fluid balance and flush out excess sodium. Dehydration can signal your body to retain water.
Adjust Dosage: If taking creatine, consider skipping the loading phase and opting for a consistent, lower daily dose. For protein, split larger servings into smaller ones throughout the day.
Switch Products: If you suspect lactose intolerance, try a plant-based protein or a high-quality whey protein isolate. For bloating from artificial sweeteners, find an unsweetened or naturally flavored alternative.
Monitor Sodium Intake: Be mindful of your overall dietary sodium, as supplements can contribute to a high-sodium diet.
Increase Potassium Intake: Counteract the effects of sodium by eating potassium-rich foods like bananas, spinach, and avocados.
Incorporate Exercise: Regular physical activity and movement can help circulate fluids and reduce localized swelling.

Comparison Table: Supplements and Water Retention


Supplement	Primary Cause of Fluid Effect	Effect on Water Retention	Management Strategy
Creatine	Osmotic effect pulls water into muscle cells.	Direct (Intracellular)	Skip loading phase, stay hydrated.
Whey Protein	Lactose intolerance or digestive strain.	Indirect (Digestive Bloating)	Switch to isolate or plant-based protein.
Pre-Workout	High creatine, caffeine, sodium, or sugar alcohols.	Both Direct and Indirect	Check ingredients, start with a lower dose.
Artificial Sweeteners	Poor digestion and fermentation by gut bacteria.	Indirect (Digestive Bloating)	Choose unsweetened or naturally sweetened options.

Conclusion

For those asking "what supplement causes water retention?", creatine is the most direct and common answer, but its effect is temporary and intracellular, supporting muscle function rather than causing unhealthy subcutaneous swelling. Other supplements, particularly protein powders and pre-workouts, can cause bloating and digestive-related fluid retention due to ingredients like lactose or artificial sweeteners. By understanding the specific mechanisms behind these effects, users can make informed choices about dosage, product type, and complementary lifestyle habits to effectively manage or mitigate unwanted fluid retention. Proper hydration, moderation, and checking ingredient lists are the best defenses against supplement-induced bloating and water weight.

Frequently Asked Questions

Yes, especially during a loading phase, creatine can cause a temporary increase in water weight that may make you feel and look more bloated or puffy. However, this fluid is drawn into the muscles (intracellularly), not under the skin, so it differs from unhealthy, subcutaneous swelling.

Bloating from protein powder is often due to digestive issues rather than true water retention. Common causes include lactose intolerance from dairy-based proteins (whey, casein), artificial sweeteners like sugar alcohols, or added fibers that can be hard to digest.

Protein powder does not directly cause physiological water retention in the same way creatine does. Any weight changes are typically related to muscle growth or digestive bloating from poorly digested ingredients, not from fluid buildup caused by the protein itself.

To reduce water retention from creatine, you can skip the loading phase and use a lower, daily maintenance dose. Staying well-hydrated is also crucial, as drinking more water helps your body manage fluid balance effectively.

Yes, supplements containing high levels of sodium, such as some pre-workout formulas, can contribute to water retention. The body holds onto water to maintain the correct electrolyte balance, so a high sodium intake increases this effect.

Ingredients like sugar alcohols in flavored supplements and multi-ingredient pre-workouts can cause digestive distress and bloating. An imbalance of electrolytes, which can be affected by supplements, is also a key factor in fluid regulation.

Yes, especially with supplements like creatine, a rapid weight gain of 1–2% is common and is primarily due to temporary water retention inside muscle cells, not fat gain. This typically normalizes after a few weeks.