Is Pepsi Cola Considered a Clear Liquid? The Surprising Answer for Dieters and Procedures

December 7, 2025 •

3 min read

Despite its dark appearance, medical guidelines for clear liquid diets often classify certain versions of Pepsi Cola as an acceptable clear liquid. The criteria for a 'clear liquid' goes beyond mere transparency, focusing on whether a liquid leaves behind solid, undigested residue in the intestinal tract.

Quick Summary

This article explains why some dark-colored sodas, including specific types of Pepsi, are allowed on a clear liquid diet. It outlines the medical definition of a clear liquid, differentiates between regular and diet versions, and provides a comparison table of common beverages for those preparing for a medical procedure or following a restricted diet.

Key Points

Medical Definition: A 'clear liquid' is defined by its lack of solid residue, not its transparency, for procedures like a colonoscopy.
Pepsi is Often Permitted: Many medical guidelines allow Pepsi Cola and other dark colas on a clear liquid diet because they don't leave solid residue.
Dye Restrictions: The key exception for beverages is avoiding red and purple dyes, as they can interfere with examination results by mimicking blood.
Regular vs. Diet: Both regular and diet colas are typically acceptable, but those with diabetes should be mindful of the high sugar content in regular soda.
Adherence is Crucial: Following the prescribed diet is essential for accurate procedure results and to avoid having to reschedule.
Short-Term Use: A clear liquid diet is a temporary, medically supervised regimen and should not be confused with a healthy, balanced diet.

Understanding the Definition of a Clear Liquid

When preparing for a medical procedure like a colonoscopy, or managing certain digestive issues, patients are often instructed to follow a clear liquid diet. The term 'clear' can be misleading, as it is not strictly about a liquid's transparency. A clear liquid is medically defined as one that is easily digested, leaves no undigested residue in the intestinal tract, and is liquid at room temperature. While water, apple juice, and gelatin are obvious examples, the inclusion of certain dark sodas like cola often surprises people.

The Reason Dark Sodas Can Be 'Clear'

For medical purposes, a liquid's effect on the digestive system is more important than its visual appearance. The dark caramel coloring in colas like Pepsi is processed by the body in a way that does not leave a significant solid residue. This is in stark contrast to milk, which contains proteins that curdle and leave solid residue, or orange juice with pulp, which contains fibrous material. The key is the absence of solid food particles, dairy, or dense, pulpy ingredients.

Regular vs. Diet Pepsi on a Clear Liquid Diet

While both regular and diet colas are often permitted on a clear liquid diet, there are considerations for both. Diet sodas, including Diet Pepsi, are generally fine. Regular colas contain a high amount of sugar, which some patients with diabetes may need to monitor. However, from a clear liquid diet's primary objective—leaving minimal intestinal residue—both are typically acceptable choices, as long as they are not red or purple colored. Certain red or purple artificial colorings can interfere with medical imaging during procedures like a colonoscopy, as they can be mistaken for blood.

Comparison of Common Beverages on a Clear Liquid Diet

This table provides a quick reference for common beverages and their suitability for a clear liquid diet, based on standard medical guidelines.


Beverage	Acceptable on Clear Liquid Diet?	Notes
Pepsi Cola (Regular & Diet)	Yes	Dark coloring does not affect procedure imaging; leaves no residue. Avoid red or purple versions.
Water (plain or flavored)	Yes	Standard and most common clear liquid.
Apple Juice (strained)	Yes	Should be pulp-free. White grape juice is also acceptable.
Orange Juice (with pulp)	No	Contains pulp and is not transparent.
Milk or Cream	No	Dairy products curdle and leave residue.
Coffee or Tea (black)	Yes	Can be consumed without milk, cream, or non-dairy creamer.
Clear Broth (chicken or beef)	Yes	Must be clear and free of solid particles like noodles or vegetables.
Red/Purple Gatorade or Kool-Aid	No	Artificial red and purple dyes can interfere with procedure results.
Smoothies	No	Contain fibrous fruit and other solids.

Why Following the Protocol is Critical

Failing to adhere strictly to a clear liquid diet before certain procedures can have serious consequences. If solid residue is left in the digestive tract, it can obstruct the doctor's view, leading to an incomplete or inaccurate exam. This could mean the procedure must be rescheduled, causing delays in diagnosis and treatment. For this reason, healthcare providers emphasize the importance of following all preparation instructions carefully. You can find more information about therapeutic diets from authoritative sources like the National Center for Biotechnology Information.

Conclusion

In summary, the question of whether Pepsi Cola is considered a clear liquid is a matter of medical definition rather than visual appearance. For the purposes of a pre-procedural clear liquid diet, dark colas are often acceptable because they do not leave solid residue behind. However, this does not apply to all dark liquids, such as certain pulpy juices or dairy products. Always consult with your healthcare provider for specific instructions, but rest assured that in many medical scenarios, a can of Pepsi can be part of your clear liquid regimen.

The Health Context of Clear Liquids

It is important to remember that a clear liquid diet is typically a short-term, medically necessary plan. While Pepsi is sometimes permitted, this does not imply it is a healthy choice for daily consumption. The diet is not designed to be nutritionally complete and is used temporarily to prepare the digestive system. For long-term health, a balanced diet is always recommended. Always follow the specific instructions from your medical team, as protocols can vary depending on the specific procedure or condition being managed.

Frequently Asked Questions

Pepsi is considered a clear liquid in a medical context because it does not contain any solid food particles or pulpy ingredients that leave undigested residue in the intestinal tract. The dark caramel coloring does not interfere with the examination, making it suitable for clear liquid diets.

Most light-colored and dark (cola) sodas without red or purple dyes are generally allowed. This includes Sprite, ginger ale, and regular and diet colas. However, any soda with red or purple coloring should be avoided, as these dyes can be mistaken for blood during a procedure.

In most cases, yes. Pepsi is commonly listed among the acceptable clear liquids for colonoscopy preparation. The key is to avoid any red or purple liquids and to follow all specific instructions from your healthcare provider regarding the diet.

A clear liquid diet consists only of transparent liquids that leave no residue, such as broth and juice without pulp. A full liquid diet includes all items from a clear liquid diet plus liquids that are thicker or not transparent, such as milk, strained cream soups, and pureed vegetables.

Yes, Diet Pepsi is an acceptable choice on a clear liquid diet. Since it is sugar-free, it is often a preferred option for diabetic patients who must monitor their sugar intake.

Artificial red and purple dyes can leave a residue in the bowel that can be mistaken for blood during the colonoscopy, which can interfere with the examination and lead to inaccurate results.

Besides cola, other common clear liquids include water (plain, carbonated, or flavored), clear fruit juices like apple or white grape, clear broth, plain gelatin (not red or purple), popsicles without fruit pieces, and tea or coffee without milk or cream.