If you experience dizziness, lightheadedness, or nausea after drinking a protein shake, you may want to reconsider how you include protein shakes in your diet.
Although there’s no research that directly connects protein shakes to dizziness and nausea, allergies, lactose intolerance, or exercise may be causing your symptoms.
You Might Have an Allergy
If a protein shake or powder causes dizziness or nausea, you may have a food allergy.
Many protein shakes and powders contain common allergens, like milk whey, casein, eggs, or soy, according to Harvard Health Publishing.
While food allergy symptoms vary from person to person, other symptoms can include:
- Hives or skin rashes
- Swelling of the face, lips, mouth, or tongue
- Difficulty breathing
- Difficulty swallowing
- Wheezing
- Shortness of breath
If you have one undiagnosed allergy, you may be allergic to other allergens found in protein shakes. Switching to a different type of protein shake or powder may relieve unpleasant symptoms.
If you’re not sure whether you have any food allergies, consider seeing an allergy specialist. They can test how your body responds to common allergens using a skin prick test or blood test, according to Cleveland Clinic.
In some cases, an allergic reaction can progress to anaphylaxis, a life-threatening condition. If you experience multiple allergy symptoms or your symptoms are severe, seek immediate medical attention.
You May Have Low Blood Sugar
Many protein powders and shakes can be high in sugar, which may lead to reactive hypoglycemia, according to Cleveland Clinic.
Reactive hypoglycemia is low blood sugar that can occur after a high-carbohydrate meal. While not fully understood, it may be triggered by simple carbohydrates, like sugars, which can cause a quick spike and then drop in blood sugar levels.
Dizziness and nausea are symptoms of reactive hypoglycemia, which can also cause:
- Shakiness
- Sweating or chills
- Anxiety and nervousness
- Hunger
- Increased heart rate
- Fatigue or weakness
- Headaches
If you experience any of these symptoms, your doctor can test your blood sugar levels to determine if you have reactive hypoglycemia.
You’re Drinking Immediately After Exercise
Drinking a protein shake too soon after a workout might make you feel sick.
According to a review published in March 2025 in the Journal of Clinical Medicine, your digestive system slows down and gastric emptying is delayed immediately following high-intensity exercise. This means anything you eat or drink stays in your digestive system longer.
If you drink a protein shake too quickly after your workout, it can sit in your stomach and cause symptoms like nausea, vomiting, or diarrhea.
This effect is more common after high-intensity exercises, like sprints, swimming, or weight lifting.
You May Be Sensitive to Dairy
According to Cleveland Clinic, whey protein found in shakes and powders contains lactose, a sugar that comes from milk.
If you are lactose intolerant, drinking whey protein may cause symptoms like nausea, vomiting, and stomach cramps, according to Mayo Clinic.
Products containing whey protein isolate may be a better choice if you have lactose intolerance. Whey protein isolate is a type of whey that is high in protein but low in lactose.
Other protein sources to try if you are sensitive to dairy include egg, pea, or rice protein.