5 Supplements to Avoid Mixing with Protein Powder

Verywell Health • January 20, 2026 • health

Key Points:

Protein powder may interfere with the absorption of certain supplements, such as iron, calcium, fiber, pre-workout formulas, and creatine, potentially causing side effects like bloating or reduced nutrient uptake.
Iron absorption can be blocked by calcium and phytates in protein powder, so it’s recommended to space iron supplements and protein powder at least two hours apart.
Combining fiber supplements with protein powder may slow digestion and reduce protein absorption while causing gastrointestinal discomfort, so spacing them out is advised.
Pre-workout supplements containing stimulants or extra protein can lead to jitters, nausea, or bloating when taken with protein powder, and creatine combined with protein powder may cause bloating or diarrhea in some individuals.
Consumers