We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is Magnesium Hydroxide?

By Deneatra Harmon
Updated Jan 31, 2024
Our promise to you
WiseGeek is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WiseGeek, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Magnesium hydroxide is a mineral supplement that works as an antacid as well as a laxative. It commonly comes in liquid or tablet form. Dosages vary depending on age, and the directions must be strictly followed to avoid magnesium overdose. Like other supplements or medications, magnesium hydroxide may cause side effects, such as stomach discomfort, vomiting and rectal bleeding, in some people. Certain medications may also interfere with the magnesium hydroxide benefits, such as antibiotics and anti-seizure medications.

This mineral supplement, which is intended only for short-term use, treats problems such as an upset stomach, heartburn, and acid indigestion. Magnesium hydroxide as an antacid is best identified as milk of magnesia. As a laxative, magnesium hydroxide relieves constipation. Overall, the supplement neutralizes stomach acid and increases the water content in the intestines, which helps to soften stool.

As a medication, magnesium hydroxide must be taken by mouth. Liquid forms of the mineral supplement, such as milk of magnesia, must be shaken first, measured with a spoon, and then taken as directed according to the label or a doctor. Other options for magnesium hydroxide include pills or chewable tablets that must also be taken accordingly with a full glass of water. Depending on the person's condition, it may take up to six hours for the mineral to relieve constipation; in general, the medicine should not be taken for longer than one week. As an antacid, milk of magnesia should resolve stomach problems in two weeks or less.

While a magnesium supplement offers the benefits of constipation and acid relief, some people may experience side effects. Some of these include an upset stomach or stomach cramps. Medical attention should be sought immediately if these symptoms occur, plus any other symptoms such as diarrhea, vomiting, loss of appetite, or rectal bleeding. Allergic reactions such as hives or a skin rash may also result as adverse effects from the mineral supplement.

Additionally, a person must take precautions and notify his doctor of other conditions, medications or supplements that may interfere with magnesium, such as vitamin D. Prescriptions that may interact include antibiotics and medications for seizures, fungal infections, and osteoporosis. In addition, a patient with kidney disease or a woman who is pregnant or breast-feeding must consult with a doctor before taking any magnesium-based supplements, antacids or laxatives. To ensure effectiveness, this mineral should be stored at room temperature and away from extreme heat and light.

WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
By Perdido — On Oct 30, 2011

When my doctor prescribed antibiotics to treat my sinus infection, I did not know that I would be unable to take my magnesium hydroxide pills at the same time. I found this out once I got home from the pharmacy and read the information packet that came with the antibiotics.

It said that I should not take any antacids within a few hours of taking this medicine. I could take an antacid one hour before taking the antibiotic or several hours afterward.

The problem was that I needed to take the antibiotic with food in order to avoid getting an upset stomach. Well, I have to take an antacid either right before eating or right after to avoid heartburn, and I couldn't do both.

By OeKc05 — On Oct 29, 2011

@kylee07drg – You're not the only one! I love magnesium hydroxide tablets. I was even tempted to eat more than I needed, but I knew this could cause discomfort, so I resisted the urge.

I hate having to drink a full glass of water with them, though. It washes away all the good flavor! Plus, it makes me feel really full, especially since I have just eaten when I take them.

I keep the tablets in my purse, because I know I usually need them after eating a big meal at a restaurant. When I eat small meals at home, I'm usually okay, but with richer foods and bigger servings, I have to have it.

By lighth0se33 — On Oct 28, 2011

I frequently get constipation, and I also experience heartburn. So, magnesium hydroxide was the perfect choice for my condition.

I got milk of magnesia to treat the constipation. I was happy to learn that it would also ease my acid reflux.

It gently softened my stools and didn't give me diarrhea at all. The first day I took it, I noticed that I didn't have any heartburn, either.

Milk of magnesia is one of those remedies that I will always keep in my medicine cabinet. I don't use it on a regular basis, but I have it for when I need it.

By kylee07drg — On Oct 28, 2011

Am I the only one who loves the taste of those magnesium hydroxide chewable tablets? I used to use them for heartburn relief, and I cherished the flavor and texture!

I normally don't get heartburn, but I went through a phase in college where I got it every day. I found these pills, and I was delighted to discover that they didn't taste bitter or disgusting.

Once I started to chew them, they seemed to melt on my tongue. There was almost a fizzy sensation and a taste that reminded me of chewable vitamins, which I also love. I'm glad I don't have heartburn anymore, but I actually miss eating the tablets!

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.