Whey Protein

Medically Reviewed by Melinda Ratini, MS, DO on March 31, 2022
2 min read

Whey is a product of cheese making -- it’s the watery part of milk that separates from the curds. Some people use whey as a source of protein or as a supplement for health conditions.

Protein powders are popular with athletes, particularly those doing strength training. They provide a good source of nutrients and amino acids. Some people take whey protein because they are lactose intolerant or allergic to other protein sources, like eggs or soy.

Several studies have found that whey protein, when combined with strength training, might increase strength, muscle size, and lean body mass.

A few studies of whey protein as a treatment have been promising. It's been found to help prevent excessive weight loss in people with HIV.

When compared to cow’s milk protein, whey may help prevent the development of atopic dermatitis or eczema in young children. More research is needed. Talk to your child's health care provider before giving your baby whey protein.


Optimal doses of whey protein have not been established for any condition. Quality and active ingredients in supplements may vary widely from maker to maker. This makes it very hard to establish a standard dose.

Whey protein is found in milk in small amounts. In the process of turning milk into cheese, whey protein is removed.

It is always a good idea to discuss any supplement with your doctor, especially if you are pregnant or breastfeeding.  

Here are other guidelines for taking whey protein:

  • Side effects. Most people tolerate whey protein well. High doses can cause nausea, increased bowel movements, thirst, cramps, bloating, and headache.
  • Risks. People with milk allergy or sensitivity should not use whey protein. It could cause an allergic reaction. If you have kidney disease, check with a doctor before using any type of protein powder.
  • Interactions. If you take any medicines or supplements regularly, talk to your health care provider before you start using whey protein. It could interact with antibiotics and certain medicines such as alendronate (Fosamax) for osteoporosis or levodopa for Parkinson's disease.