How to Drink Citrate of Magnesium

Co-authored by Bailey Cho Medically reviewed by Luba Lee, FNP-BC, MS

Last Updated: November 16, 2024 Fact Checked

Magnesium is an essential mineral that’s already in your body. It helps regulate your nervous system and muscles. One of the best ways to get additional magnesium is to take it in the form of magnesium citrate. Your doctor may tell you to drink it to relieve occasional constipation or to prepare you for a colonoscopy. It works by increasing the amount of water in your intestines, making it easier for you to have a bowel movement.^{[1]
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Go to source} In most cases, magnesium citrate is safe for everyone over 2 years of age, but always check with your doctor before using it.^{[2]
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Method 1

Method 1 of 2:

Relieving Constipation

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Talk to your doctor to see if magnesium citrate is right for you. In most cases, magnesium citrate is safe if you take it to relieve constipation. However, some present or past health issues can make regular or higher doses less safe. Talk to your doctor if you:^{[3]
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- Have stomach pain or nausea
- Have ever had kidney disease
- Have experienced a sudden change in your bowel habits lasting more than 2 weeks
- Are vomiting regularly due to some condition
- Are on a low-sodium or low-magnesium diet
- Are taking medications to treat HIV^{[4]
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- Are taking vitamin D, sodium phosphate sulfonate, or some antibiotics (ciprofloxacin, doxycycline, gatifloxacin, levofloxacin, tetracycline).^{[5]
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2
Drink magnesium citrate on an empty stomach or wait 2 hours after eating or taking medication. The laxative effects work best when your stomach is empty or nearly empty. If you’ve only had a small snack or bite to eat, you can wait just 1 hour instead of 2.^{[6]
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- If you take other supplements or medications, take them at least 2 hours before or after taking magnesium citrate.^{[7]
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Take 195 to 300 millilitres (6.6 to 10.1 fl oz) at a time or in divided doses. How much you drink to relieve constipation depends on your age. If you’re giving it to a child under 2 years of age, talk to your doctor or pediatrician first. Otherwise, stick to the basic recommendations:^{[8]
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- Anyone over 12 years of age: 195 to 300 millilitres (6.6 to 10.1 fl oz) with 240 mL (8 fl oz) of water in a single dose or divided doses.
- Children 6 to 12 years of age: 90 to 210 millilitres (3.0 to 7.1 fl oz) with 240 mL (8 fl oz) of water in a single dose or divided doses.
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Drink 8 fl oz (240 mL) of water after swallowing the dose. Drinking a full glass of water will prevent serious side effects like dehydration.^{[9]
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Research source} You might find it easier to drink magnesium citrate after letting the bottle chill in the refrigerator.^{[10]
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Go to source} You don’t have to chill it, but it can improve the taste.^{[11]
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- To help mask the taste, mix the liquid with a citrus-flavored drink like Sprite or 7 Up. Follow up with 8 fluid ounces (240 mL) of water.^{[12]
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- If you’re an adult, you can take up to 10 fluid ounces (300 mL) of magnesium citrate per day. Take it all at once or in 2 separate doses.^{[13]
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- If you’re giving it to a child aged 6 to 12, don’t give them more than 210 millilitres (7.1 fl oz) per day unless your pediatrician says it’s okay.^{[14]
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Expect a bowel movement within the next 30 minutes to 6 hours. How soon it takes the medication to kick in depends on your digestive system and how much you drank. Make sure you have access to a bathroom after taking magnesium citrate so you're not forced to uncomfortably hold it in.^{[15]
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- You may experience excess gas or mild stomach cramps while the magnesium citrate is taking effect.^{[16]
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- If you don't have a bowel movement after taking magnesium citrate, call your doctor because it could be a sign of some other condition.^{[17]
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Call your doctor if you have any severe side effects. It’s rare to experience serious side effects when taking magnesium citrate.^{[18]
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Research source} In most cases, diarrhea, loose stools, and stomach pain are common (and uncomfortable) side effects.^{[19]
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Research source} Any severe reaction could be a sign of some other condition, so stop taking magnesium citrate and call your doctor if you experience:^{[20]
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- Irregular or slow heartbeat
- Nausea, drowsiness, or weakness
- Confusion
- Skin rash, itching, or hives^{[21]
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- Swelling of the face, lips, tongue, or throat
- Facial flushing or redness
- Sweating
- Muscle weakness
- Trouble breathing
- Severe abdominal pain, watery diarrhea, bloody stools, or rectal bleeding

Method 2

Method 2 of 2:

Drinking Magnesium Citrate before a Colonoscopy

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Eat low-fiber foods 2 to 3 days before your appointment. Your bowels need to be as empty as possible in order for the doctor to get an accurate reading from the colonoscopy.^{[22]
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Go to source} Low-fiber foods like white breads and grains, white rice, and whole grain-free cereals are all good things to eat while preparing for your appointment.^{[23]
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- Tofu, eggs, and smooth nut butters are also delicious choices!^{[24]
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- Avoid whole grains (like brown rice, whole wheat bread and pasta), nuts, legumes, fruits with skin or seeds, and tough meats with gristle because they can clog up your digestive tract.^{[25]
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- You can eat canned or cooked vegetables without skins, like mushrooms, peeled carrots, peeled cucumbers, peeled potatoes, turnips, and asparagus tips. Corn, potatoes with skin, brussels sprouts, lima beans, and onions are off-limits for now.^{[26]
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Go on a clear liquid diet the day before your appointment. Only consume clear liquids like water, black tea, coffee (without milk or creamer), light-colored juices (apple, white grape, white cranberry), broths, and sports drinks the day before your appointment.^{[27]
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Research source} Avoid red or purple-colored juices, alcohol, heavy soups, and milk because they can affect the reading your doctor will get from the procedure.^{[28]
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- Continue fasting until your appointment and don't drink anything (including water) for 3 hours before your arrival time.^{[29]
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3
Refrigerate the bottles at least one hour before you plan to drink them. Magnesium citrate tastes bitter, salty, and metallic.^{[30]
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- Don't put it in the freezer, and store it in a closed container at room temperature.^{[32]
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- Buy lemon or lime-flavored magnesium citrate to mask the metallic, bitter taste.^{[33]
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Drink a 10 fl oz (300 mL) bottle the night before your appointment. Around 6 PM, down an entire bottle of magnesium citrate. Follow up with an 8 fl oz (240 mL) glass of water to push it through your system.^{[34]
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- Depending on your weight, age, and particular condition, your doctor may tell you to only drink half a bottle at a time.^{[35]
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- You may have gas, slight stomach pain, or diarrhea after taking magnesium citrate—these are common side effects that will ease up once you have a bowel movement.^{[36]
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Don't eat any solid foods for the rest of the night and the next morning. In most cases, you'll need to avoid eating any solid foods or milk products until your appointment is over. Juice, Jell-O, tea, popsicles, sports drinks, broths, and hard candies are okay, as long as they're not red or purple.^{[37]
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- Red or purple dye in liquids can make it hard for the doctor to see the lining of your colon, skewing the results.^{[38]
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Drink a second bottle 5 hours before your appointment. The final 10 fl oz (300 mL) bottle of magnesium citrate will clear your bowels completely before the colonoscopy. Chase it down with 8 fluid ounces (240 mL) of water just like you did with the first bottle.^{[39]
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- It can take anywhere from 30 minutes to 6 hours to feel the effects, so stay near a bathroom if you can.^{[40]
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- Keep fasting and don't have anything else to drink before your appointment (including water).^{[41]
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Tips

If you’re preparing to have a colonoscopy, eat a low-fiber diet 2-3 days before your appointment.^{[42]
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Before a colonoscopy, make sure you get your preparation instructions well in advance of the procedure. Your doctor might advise you to pick up bowel prep supplies, such medicated wipes or Vaseline.^{[43]
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Wear loose, comfortable clothes when you go to your appointment.^{[44]
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Warnings

Do not take magnesium citrate for more than one week, unless your doctor advises you to do so.^{[46]
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