Common and Rare Side Effects of Ensure Shakes

December 28, 2025 •

4 min read

According to user reports, common side effects of Ensure shakes often include digestive issues such as gas, bloating, and constipation. While a convenient source of nutrition, Ensure's ingredients can sometimes cause adverse reactions, particularly in individuals with sensitive digestive systems or specific allergies. Understanding these potential issues is crucial for anyone considering or regularly consuming these supplements.

Quick Summary

Ensure shakes can cause digestive upset like diarrhea, gas, and bloating in some individuals, often due to ingredients like corn syrup, certain fibers, or lactose. Rare side effects may also occur. Sensitivities to ingredients, improper consumption, or underlying health conditions can trigger adverse reactions.

Key Points

Digestive Upset is Common: Many individuals experience side effects such as gas, bloating, diarrhea, or constipation, especially when first starting Ensure.
Ingredient Sensitivities Play a Role: Certain ingredients, including corn maltodextrin, lactose, soy protein, and annatto dye, can trigger sensitivities or allergic reactions.
Rare but Serious Effects Exist: In rare instances, side effects like irregular heartbeat or severe allergic reactions can occur. High vitamin K content can also interfere with blood thinners like Warfarin.
Managing Side Effects is Possible: Symptoms can often be alleviated by introducing the product slowly, staying hydrated, sipping slowly, or switching to alternative formulas like the plant-based version.
Consult a Healthcare Provider: If side effects are persistent, severe, or if you have pre-existing health conditions, it is crucial to consult a doctor for personalized advice.

Common Digestive Side Effects

Many people report gastrointestinal discomfort after drinking Ensure shakes, especially when they first start using them. These symptoms typically subside as the body adjusts, but they can persist for some individuals.

Gas and Bloating

Gas and bloating are among the most frequently reported side effects. This can be caused by several factors within the shake's formula:

Carbohydrate Content: Ingredients like corn maltodextrin and short-chain fructooligosaccharides (FOS) are carbohydrates that can be fermented by gut bacteria, leading to gas production.
Swallowed Air: Gulping the shake down quickly can also cause you to swallow excess air, contributing to bloating.
Sugar Alcohols: Some sugar-free Ensure varieties may contain sugar alcohols, which are known to cause gas and bloating in sensitive individuals.

Constipation

Some people experience constipation, particularly if they are not used to the fiber content in certain Ensure versions or are not drinking enough additional fluids. While some varieties contain added fiber to promote regularity, a sudden increase in fiber intake without adequate hydration can have the opposite effect.

Diarrhea

Conversely, diarrhea is also a possible side effect, especially for elderly individuals or those with sensitive digestive systems. High amounts of artificial sweeteners like sorbitol or high concentrations of certain ingredients can have a laxative effect.

Ingredient-Specific Sensitivities

Certain ingredients in Ensure can cause issues for people with specific allergies or intolerances.

Lactose Intolerance

Most standard Ensure products contain a small amount of lactose, and while many with mild lactose intolerance can consume it without issue, some individuals may still experience discomfort. For those with severe intolerance, alternative products or plant-based Ensure options are available.

Allergens

Ensure contains common allergens like milk and soy protein isolates, which can cause allergic reactions in sensitive individuals. Symptoms can range from mild digestive upset to more serious issues like hives, swelling, or trouble breathing.

Corn Syrup

For some people, corn syrup and corn maltodextrin can be an irritant to the digestive system. The high glycemic index of maltodextrin has also been linked to potential issues with blood sugar levels.

Annatto Dye

The natural food coloring annatto, used in some Ensure products, has been linked to intestinal upset and potential allergic reactions in some users.

Rare and Serious Side Effects

While less common, some users have reported more serious side effects. It is important to monitor your body's reaction and consult a healthcare provider if you experience any of these symptoms.

Cardiac Issues: In rare cases, individuals have reported irregular heartbeat. This is often associated with pre-existing conditions or interactions with certain medications, particularly blood thinners like Warfarin, due to the high vitamin K content in some Ensure products.
Allergic Reactions: Severe allergic reactions, although rare, can occur. Symptoms to watch for include rash, severe dizziness, or trouble breathing. Seek immediate medical attention if these symptoms appear.
Medication Interactions: The high vitamin K content in some Ensure formulas can interfere with blood-thinning medications like Warfarin. Patients on these medications should consult their doctor before consuming Ensure.

Comparison of Ensure Types and Potential Side Effects


Feature	Ensure Original	Ensure Plant-Based	Ensure High Protein
Protein Source	Milk and Soy	Plant-Based (Pea)	Milk Protein Concentrate
Lactose Content	Contains some lactose	Lactose-free	Contains some lactose
Key Differences	Balanced standard formula	Suitable for lactose intolerance	Higher protein concentration
Common Side Effects	Gas, bloating, diarrhea	Lower risk of dairy-related issues, but new fiber source can cause gas	Potential for similar digestive issues due to ingredients

Managing Side Effects

If you experience side effects from Ensure, there are several steps you can take to mitigate the issues:

Introduce Gradually: Start with smaller portions to allow your digestive system to adjust.
Hydrate Adequately: Drink plenty of water throughout the day, especially if you are consuming fiber-rich Ensure products.
Consume Slowly: Sip the shake slowly rather than gulping it down to reduce the amount of air you swallow.
Switch Formulations: If you are lactose intolerant, consider switching to the Plant-Based formula. If you suspect an ingredient sensitivity, compare labels and try an alternative.
Consult a Professional: Always discuss any persistent or severe side effects with a healthcare provider to rule out underlying health issues.

Conclusion

While Ensure shakes provide a convenient and balanced source of nutrition, they are not without potential side effects. Many users experience temporary or mild digestive issues, such as gas, bloating, and altered bowel habits, especially when first starting consumption. These issues are often related to ingredient sensitivities, such as lactose or corn products, and can often be managed with simple adjustments like consuming the product slowly and staying hydrated. Rare but more serious concerns, including interactions with medication like Warfarin due to high vitamin K content, also exist. Consulting with a healthcare professional is the best course of action for anyone experiencing persistent or severe symptoms, or those with pre-existing health conditions. This ensures you can continue to meet your nutritional needs safely and effectively.

For more information on digestive health, you can visit the American College of Gastroenterology at https://gi.org/.

Frequently Asked Questions

Ensure can cause gas and bloating due to its carbohydrate content, including corn maltodextrin and FOS, which are fermented by gut bacteria. Drinking the shake too quickly can also lead to swallowing excess air.

Yes, Ensure can cause diarrhea in some people, particularly the elderly or those with sensitive digestive systems. This can be caused by artificial sweeteners, high sugar content, or a sudden change in diet.

Most standard Ensure products contain a small amount of lactose, which is tolerated by many with mild intolerance. However, those with severe intolerance should opt for the lactose-free Plant-Based formula.

Some Ensure formulas are high in vitamin K, which can interfere with blood-thinning medications like Warfarin. If you take this medication, consult your doctor before consuming Ensure.

If you experience side effects, try consuming the shake more slowly, staying well-hydrated, or switching to a different Ensure product, like the plant-based option. If symptoms persist, consult a healthcare provider.

Most common side effects, especially digestive ones, are temporary and may lessen as your body adjusts to the supplement. For persistent or severe issues, consulting a doctor is recommended.

Ensure contains milk protein concentrate and soy protein isolate, which are common allergens. Always check the ingredient list for potential allergens.

Yes, a serious allergic reaction is rare but possible, especially for those sensitive to milk, soy, or food dyes like annatto. Seek immediate medical help for symptoms like rash, swelling, or trouble breathing.

Yes, alternatives include homemade smoothies with lactose-free milk or plant-based protein powders, and certain brands formulated for sensitive stomachs.

To prevent digestive issues, start with a small serving, drink it slowly, and increase your water intake. Choosing a fiber-free or plant-based version may also help.