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Milk of Magnesia
Used for Constipation
Used for Constipation
Milk of Magnesia (magnesium hydroxide) is an over-the-counter saline laxative that's most often used to treat occasional constipation in adults and children. It helps your body have a bowel movement by pulling water into your gut. This medication can also help relieve indigestion and heartburn by neutralizing your stomach acid. It's a liquid that's taken by mouth, and side effects aren't common at recommended dosages.
What is Milk of Magnesia (magnesium hydroxide)?
What is Milk of Magnesia (magnesium hydroxide) used for?
- Occasional constipation
- Heartburn
- Sour stomach
- Indigestion
How Milk of Magnesia (magnesium hydroxide) works
Milk of Magnesia (magnesium hydroxide) is a saline laxative. It works by drawing water into your gut. This raises the number of bowel movements you have and softens your stools, making them easier to pass.
Milk of Magnesia (magnesium hydroxide) also acts as an antacid. It neutralizes, or balances, the acid in your stomach. This helps relieve heartburn, sour stomach, and indigestion.
When does Milk of Magnesia (magnesium hydroxide) start working?Time passed since treatment started:
Drug facts
| Common Brands | Milk of Magnesia |
|---|---|
| Drug Class | Saline laxative |
| Controlled Substance Classification | Not a controlled medication |
| Generic Status | Lower-cost generic available |
| Availability | Over-the-counter |
Side effects of Milk of Magnesia (magnesium hydroxide)
The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Common Side Effects
Milk of Magnesia (magnesium hydroxide) serious side effects
Contact your healthcare provider immediately if you experience any of the following.
- Bloody diarrhea
- Severe constipation
The following Milk of Magnesia (magnesium hydroxide) side effects have also been reported
Side effects that you should report to your care team as soon as possible:
- Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
- High magnesium level—confusion, drowsiness, facial flushing, redness, sweating, muscle weakness, fast or irregular heartbeat, trouble breathing
Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome):
- Diarrhea
- Stomach cramping
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$7.97
GoodRx discount
$6.45
Pros and cons of Milk of Magnesia (magnesium hydroxide)
Pros
- Can work as soon as 30 minutes to relieve constipation
- Can be used in children (minimum age depends on the product)
- Available over the counter (OTC) and as a lower-cost generic
Cons
- Not meant for long-term use
- Might not be safe in people with kidney problems
- Need to take some other medications at a different time than Milk of Magnesia (magnesium hydroxide) to prevent drug interactions
Pharmacist tips for Milk of Magnesia (magnesium hydroxide)
- Check with your provider whether Milk of Magnesia (magnesium hydroxide) is safe for you to take if you have kidney problems, stomach pain, nausea, vomiting, or are on a low-magnesium diet.
- Drink a full glass of water (8 oz) with each dose of Milk of Magnesia (magnesium hydroxide) that you take. This helps prevent dehydration.
- Shake the Milk of Magnesia (magnesium hydroxide) bottle well before you measure out your dose. This makes sure the medication is mixed evenly throughout the solution.
- Only use the measuring spoon or dosing cup that comes with the packaging, and ask the pharmacy if you need extras. Don't use household measuring spoons or cups to measure your dose; you might take the wrong amount of medication if you use household spoons since they might not be accurate.
- Tell your provider or pharmacist about all the medications you're taking since Milk of Magnesia (magnesium hydroxide) can change the way some medications work. You might need to separate when you take Milk of Magnesia (magnesium hydroxide) from some of your other medications to prevent drug interactions.
- Stop taking Milk of Magnesia (magnesium hydroxide) and tell your provider if you don't have a bowel movement after 6 hours of taking the medication. Also contact a provider if you need to use the medication for more than 1 week. These can be signs of a more serious problem that your provider needs to check out.
- Keep Milk of Magnesia (magnesium hydroxide) out of reach of children. The medication comes in flavored liquids that children can easily take by accident. Call the Poison Control Center (1-800-222-1222) right away if your child accidentally took too much Milk of Magnesia (magnesium hydroxide).
Risks and warnings for Milk of Magnesia (magnesium hydroxide)
Milk of Magnesia (magnesium hydroxide) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Signs that your intestinal problems might be more serious
Stop taking Milk of Magnesia (magnesium hydroxide) and call your provider if you have rectal bleeding (blood that comes from your anus), stomach pain, nausea, or vomiting. Also contact your provider if you can't have a bowel movement within 6 hours after you take Milk of Magnesia (magnesium hydroxide). Let your provider know if you notice a sudden change in bowel habits over the last 2 weeks or if you've already used a laxative for more than 1 week without improvement. These could all be signs of a more serious problem that needs to be checked out by a provider.
Possible electrolyte changes
- Risk factors: Kidney problems | Magnesium-restricted diet
Milk of Magnesia (magnesium hydroxide) might not be safe in people who have kidney problems since the medication can cause an electrolyte imbalance and lead to serious side effects. Talk to your provider before you use Milk of Magnesia (magnesium hydroxide) if you have kidney problems. Your provider can discuss whether you need to limit how much magnesium you get from your diet to avoid having electrolyte imbalances.
Milk of Magnesia (magnesium hydroxide) dosage
The average cost for 1 bottle of 355ml of 1200mg/15ml of Milk of Magnesia (magnesium hydroxide) is $6.45 with a free GoodRx coupon. This is 19.07% off the average retail price of $7.97. 
Bottle of oral suspension
Bottle of oral suspension| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 355ml of 1200mg/15ml | 1 bottle | $6.45 | $6.45 |
Typical dosage for Milk of Magnesia (magnesium hydroxide)
Some Milk of Magnesia (magnesium hydroxide) products can be used for constipation only, and others for indigestion and heartburn only. The products can also have different strengths of magnesium hydroxide, which means that they can have different directions.
Make sure to read the package label carefully for instructions on how to take each specific Milk of Magnesia (magnesium hydroxide) product. Dosages of some example products are listed below.
- Each 15 mL of medication contains 1,200 mg of magnesium hydroxide.
- Adults and children aged 12 years and older: The typical dose is 30 mL to 60 mL by mouth per day. The dose can be taken all at once at bedtime or split into smaller doses throughout the day.
- Children aged 6 to 11 years: The typical dose is 15 mL to 30 mL by mouth per day. The dose can be taken all at once at bedtime or split into smaller doses throughout the day.
- Children aged 5 years and younger: Ask your child's provider.
Heartburn, sour stomach, or indigestion
- Each 5 mL of medication contains 400 mg of magnesium hydroxide.
- Adults and children 12 years and older: The typical dose is 5 mL to 15 mL by mouth with a little water.
- Children aged 11 years and younger: Ask your child's provider.
How much does Milk of Magnesia (magnesium hydroxide) cost?
To access savings, use a GoodRx coupon and pay just a fraction of the retail price.
Milk of Magnesia (magnesium hydroxide) (generic)
$6.45
What are alternatives to Milk of Magnesia (magnesium hydroxide)?
There are a number of medications that your doctor can prescribe in place of Milk of Magnesia (magnesium hydroxide). Compare a few possible alternatives below.
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