What Supplements Change Your Poop Color?

October 26, 2025 •

3 min read

According to the Cleveland Clinic, a normal stool color ranges from light to dark brown, resulting from bile pigment. However, many people find their stool color unexpectedly shifting after starting a new health regimen, leading to a common question: what supplements change your poop color? This guide explores the most frequent dietary culprits and reassures you when these changes are simply a harmless side effect of your wellness routine.

Quick Summary

This article details how various supplements, including iron, chlorophyll, and beta-carotene, can alter stool color. It explains the harmless side effects and when certain color changes may indicate a more serious underlying issue that requires medical attention.

Key Points

Iron Supplements: Taking iron can cause stools to become dark green or black due to unabsorbed mineral.
Bismuth Subsalicylate: The active ingredient in Pepto-Bismol can cause a temporary black discoloration of stool and tongue.
Chlorophyll: Supplements containing chlorophyll, the green plant pigment, can cause a noticeable green hue in your stool.
Beta-Carotene: High doses of carotenoid supplements can result in yellow or orange-colored stools.
Know the Difference: It is crucial to differentiate harmless supplement-induced color changes from serious medical issues like gastrointestinal bleeding.
Consult a Doctor: Persistent or alarming changes in stool color, especially with other symptoms, warrant medical advice.

Common Supplements that Alter Stool Color

Iron Supplements

Iron supplements are one of the most well-known causes of stool discoloration. Prescribed for conditions like anemia, they can turn your poop a very dark green or even black. This effect is due to unabsorbed iron passing through the digestive tract. The change is typically harmless but can be alarming if you are unaware. It is crucial to distinguish this from melena, a tarry, black stool caused by gastrointestinal bleeding, which is a medical concern.

Bismuth Subsalicylate (e.g., Pepto-Bismol)

This ingredient, found in many over-the-counter antacids and anti-diarrhea medications, is famous for causing black stools. The reaction occurs when the bismuth interacts with small amounts of sulfur in your digestive tract, creating a black substance called bismuth sulfide. This harmless effect is temporary and will cease once you stop taking the medication. The medication can also turn your tongue black.

Chlorophyll

Marketed for a range of health benefits, chlorophyll supplements can cause your stool to take on a noticeable green hue. Chlorophyll is the pigment that gives plants their green color, and consuming large quantities of it—either through supplements or foods like spinach and kale—can lead to green-colored stool. This is a normal and harmless effect.

Beta-Carotene and Other Carotenoids

Carotenoids are the pigments that give many fruits and vegetables their vibrant colors. High doses of supplements containing beta-carotene, often found in multivitamins, can cause your poop to turn yellow or orange. In extreme cases, excessive intake can also lead to a harmless yellowing of the skin called carotenemia.

Potential Medical Concerns and How to Tell the Difference

While supplement-induced stool changes are typically benign, it is important to know when a color change might signal a more serious health issue. Persistent or unusual changes, especially when accompanied by other symptoms, warrant a consultation with a healthcare provider.

Key Indicators for Medical Concerns:

Black, tarry stool with a foul odor (Melena): This can indicate bleeding in the upper gastrointestinal tract.
Pale, white, or clay-colored stool: This may suggest a lack of bile, which could be caused by a blocked bile duct or liver disease.
Red or maroon stool: This can signify bleeding in the lower intestinal tract, though it's often caused by red foods or dyes.

Comparison of Supplements and Their Effects


Supplement	Probable Stool Color Change	Mechanism	Typical Duration	When to be Concerned
Iron	Black, dark green	Unabsorbed iron salts oxidize in the gut.	Persists while taking supplements.	Tarry texture, strong odor, accompanying symptoms like weakness or pain.
Bismuth Subsalicylate	Black, grayish	Bismuth combines with sulfur to form bismuth sulfide.	Resolves within a few days of stopping medication.	Symptoms persist long after stopping medication.
Chlorophyll	Green	High levels of green plant pigment pass through the digestive system.	Persists while taking supplements.	Accompanied by severe diarrhea or other digestive issues.
Beta-Carotene	Yellow, orange	Excess carotenoids pass through the digestive system.	Persists while taking supplements.	Accompanied by other signs of malabsorption (like fatty stool).
Activated Charcoal	Black	Black carbon particles pass through the body unchanged.	Temporary; stops when usage stops.	Accompanying symptoms of digestive distress.

Tips for Managing and Identifying Supplement-Related Changes

To help identify the cause of a change in stool color, consider the following steps:

Keep a Log: Track your supplement intake and any resulting changes in stool color. This can help you isolate the cause if you take multiple supplements.
Pause and Observe: If you notice a color change, try stopping the suspected supplement for a few days to see if your stool returns to its normal color.
Consult a Professional: Always talk to a doctor or pharmacist before starting a new supplement, especially if you have pre-existing digestive issues.
Hydrate: Staying properly hydrated can often help regulate digestive transit time, which can sometimes influence stool color.

Conclusion

For most people, a shift in stool color after taking a new vitamin or mineral supplement is a benign and temporary side effect. The color change is typically a visual sign of the supplement's ingredients passing through your system. While iron, chlorophyll, and beta-carotene are common culprits, it is always important to monitor your body's response and be aware of any accompanying symptoms that may signal a more serious condition. Always consult a healthcare professional with any persistent or concerning changes to your digestive health.

References

For more information on digestive health, you can visit the Cleveland Clinic's detailed guide to stool colors: https://my.clevelandclinic.org/health/articles/stool-poop-color.

Frequently Asked Questions

If you recently started taking an iron supplement or a medication containing bismuth subsalicylate (like Pepto-Bismol), the black color is a common and harmless side effect. The mineral or medication reacts in your digestive tract and can cause temporary darkening of the stool.

Yes, green poop can be caused by supplements containing chlorophyll, the green pigment in plants. Iron supplements can also sometimes cause a greenish-black color. The color is not a cause for concern.

Stools that appear yellow or orange can result from taking high amounts of carotenoid supplements like beta-carotene. As long as the change is not accompanied by other symptoms of malabsorption, like greasy or foul-smelling stool, it is likely a harmless side effect.

A black stool from a supplement like iron is generally not tarry or sticky and lacks a foul odor. Conversely, a tarry, sticky, very foul-smelling black stool, known as melena, is a sign of internal bleeding and requires immediate medical attention.

The color change will typically persist as long as you are taking the supplement. Once you stop, your stool color should return to normal within a few days. If it does not, consult a doctor.

Yes, many multivitamins contain minerals like iron or pigments like beta-carotene that can alter stool color. The effects are harmless and depend on the specific ingredients and dosages in your multivitamin.

First, consider your diet and supplement intake. If the change is sudden and coincides with a new supplement, it is likely harmless. However, if the change is persistent, extreme (like pale or tarry black), or accompanied by other symptoms like pain or weakness, it is best to consult a healthcare professional.