How to avoid constipation when taking calcium supplements

November 17, 2025 •

4 min read

According to research, a significant number of people who take calcium supplements report experiencing constipation. The good news is that with a few simple adjustments to your diet, hydration, and supplement routine, you can effectively navigate and avoid constipation when taking calcium supplements, ensuring your bone health doesn't come at the cost of your digestive comfort.

Quick Summary

Constipation from calcium supplements can be managed with strategic adjustments. Increase fiber and fluid intake, split daily doses, and consider switching from calcium carbonate to calcium citrate. Adding magnesium can also help promote regular bowel movements. Regular exercise supports overall digestive health to minimize discomfort.

Key Points

Choose Calcium Citrate: Opt for calcium citrate over calcium carbonate, as it is generally less constipating and easier to absorb.
Split Your Daily Dose: Take no more than 500-600 mg of calcium at one time to improve absorption and reduce digestive strain.
Increase Fiber and Hydration: Boost your daily fiber intake and drink plenty of water to soften stools and promote regularity.
Add Magnesium: Include a magnesium supplement or a calcium-magnesium blend, as magnesium helps relax intestinal muscles and counteracts calcium's constipating effects.
Stay Active: Regular physical activity helps stimulate bowel movements and supports overall digestive health.
Talk to Your Doctor: Consult a healthcare provider if constipation persists, as they can help find the best supplement and dosage for your needs.

Understanding the Connection Between Calcium and Constipation

Some people find that calcium supplements cause an unpleasant slowing of their digestive system, leading to constipation, gas, and bloating. While the exact mechanisms are still being studied, experts believe that calcium can affect intestinal motility, or the movement of food through your gut. Additionally, excessive calcium may reduce fluid secretion in the intestines, resulting in hard, dry stools that are difficult to pass. Calcium carbonate, a popular and inexpensive form of calcium, is most frequently associated with these constipating side effects. By contrast, calcium citrate is generally better tolerated.

Optimize Your Intake to Reduce Side Effects

To minimize the risk of digestive issues, it's crucial to be mindful of how you take your calcium supplement. Simply changing your timing or dosage can have a big impact on your gut health.

Strategically Timing Your Doses

Split Your Daily Dose: The body can only absorb about 500-600 mg of elemental calcium at one time. If your daily requirement is higher, split the dose into two or three smaller portions and take them throughout the day. This reduces the burden on your digestive system.
Take with Food: For most types of calcium, particularly calcium carbonate, taking your supplement with a meal helps improve absorption. The stomach acid produced during digestion helps break down the supplement more effectively. Calcium citrate is the exception and can be taken with or without food.
Stay Consistent: Try to take your calcium at the same times each day to establish a routine. A regular schedule can help regulate your bowel movements.

Lifestyle and Diet Changes for Relief

Supplements are only one piece of the puzzle. Supporting your digestive health through your overall lifestyle can help counteract the constipating effects of calcium.

Prioritize Fiber and Fluids

Increase Dietary Fiber: Fiber adds bulk to your stool, making it softer and easier to pass. Aim for the recommended 25-30 grams of fiber per day by incorporating more fruits, vegetables, whole grains, and legumes into your meals.
Drink Plenty of Water: Hydration is essential for keeping stool soft. Fiber without adequate water can actually worsen constipation. Make sure to drink at least 8 glasses of water throughout the day, and more if you are physically active.
Consider a Fiber Supplement: If diet alone isn't enough, adding a fiber supplement like psyllium husk can be helpful. Always increase your fiber intake gradually and drink extra water to avoid gas and bloating.

The Importance of Physical Activity

Move Your Body: Regular exercise stimulates the muscles of your intestines, helping to keep things moving. A daily 20-30 minute walk can be very effective.
Avoid Prolonged Sitting: If you have a sedentary job, take frequent breaks to stand up and walk around. This simple habit can promote better digestion.

Choosing a Different Calcium Supplement

If lifestyle and timing adjustments aren't enough, it might be time to switch up your supplement.

Compare Calcium Forms


Calcium Type	Common Forms	Cost	Stomach Sensitivity	Constipation Risk	Absorption	Notes
Calcium Carbonate	Tums, Oscal, Caltrate	Inexpensive	Requires stomach acid	Highest risk	Good, with food	Most common and least expensive. Often contains the highest elemental calcium per dose.
Calcium Citrate	Citracal	Moderate to high	Does not require stomach acid	Lower risk	Good, with or without food	Recommended for those with low stomach acid or taking acid-reducing medication. Less elemental calcium per pill.
Calcium Phosphate	Various brands	Higher	Requires stomach acid	Low risk	Good	Well-tolerated with less gas and bloating for some.

Consider Calcium with Magnesium

Counteract the Constipation: Magnesium has a natural laxative effect that can help counteract the constipating effects of calcium. Many supplement manufacturers offer a combined calcium and magnesium formula.
Proper Ratio: A common and effective ratio is 2:1 (two parts calcium to one part magnesium), but speak to a healthcare provider to find the right balance for your needs.
Take at Separate Times: Some experts suggest taking your calcium and magnesium supplements at different times of the day to avoid potential absorption interference.

When to Talk to a Doctor

While these strategies can effectively manage supplement-related constipation, persistent issues may signal an underlying problem. If you experience chronic constipation (three or fewer bowel movements per week) or notice blood in your stool, it's essential to consult a healthcare professional. They can help rule out other health conditions, check for drug interactions, and provide a personalized treatment plan.

Conclusion

Constipation from calcium supplements is a manageable issue. By understanding the causes and implementing simple, effective strategies, you can maintain your bone health without compromising your digestive comfort. Optimizing your supplement timing and dosage, increasing your fiber and water intake, staying physically active, and considering a different supplement type or a calcium-magnesium combination can all make a significant difference. Listening to your body and consulting a healthcare provider for personalized advice are the most important steps to finding the right solution. For more resources on managing side effects, explore the National Institutes of Health fact sheets on dietary supplements.

Frequently Asked Questions

Calcium citrate is generally considered the least likely form of calcium to cause constipation. It is more easily absorbed and does not require as much stomach acid as calcium carbonate, which is known for its higher risk of causing constipation and bloating.

Calcium supplements can cause constipation by slowing down intestinal motility, or the movement of food through your digestive system. They can also reduce fluid secretion in the gut, which results in harder, drier stools.

Yes, taking magnesium can help. Magnesium has a natural laxative effect, promoting muscle relaxation in the intestines and drawing water into the colon to soften stools. A balanced calcium-magnesium supplement may counteract the constipating effects of calcium.

Focus on increasing your intake of dietary fiber and fluids. Add more high-fiber foods such as fruits, vegetables, whole grains, and legumes to your meals, and make sure to drink at least 8 glasses of water daily.

You should split your daily calcium dose. The body can only absorb a limited amount at one time (around 500-600 mg), so taking smaller doses throughout the day improves absorption and reduces the likelihood of side effects like constipation.

Yes, regular physical activity is very important. Exercise helps stimulate intestinal muscle activity, which promotes more regular bowel movements and supports overall digestive health.

You should see a healthcare professional if you experience chronic constipation (fewer than three bowel movements a week), notice blood in your stool, or if symptoms persist despite lifestyle adjustments. They can help determine the best course of action for your situation.