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Antacid (Oral)

Class Name: antacid (Oral route)

Commonly used brand name(s)

In the U.S.

  • Alternagel
  • Brioschi
  • Dewee's Carminative
  • Mag-Gel 600
  • NexIUM
  • Pepto Bismol
  • Phillips Milk of Magnesia
  • Riopan
  • Rolaids

In Canada

  • Alka-Seltzer Relief Chews - Heartburn
  • Alumag
  • Amphojel
  • Amphojel 500
  • Antacid
  • Antacid Plus
  • Antacid Stomaax
  • Antacid Stomaax Plus Simethicone Antiflatulent
  • Bismuth Extra Strength
  • Bismuth Original Formula
  • Calcium Antacid Extra Strength
  • Compliments Bismuth - Regular Strength

Available Dosage Forms:

  • Gel/Jelly
  • Tablet
  • Suspension
  • Tablet, Chewable
  • Capsule, Liquid Filled
  • Solution
  • Capsule
  • Granule
  • Tablet, Effervescent
  • Powder

Uses for this Medicine

Antacids are taken by mouth to relieve heartburn, sour stomach, or acid indigestion. They work by neutralizing excess stomach acid. Some antacid combinations also contain simethicone, which may relieve the symptoms of excess gas. Antacids alone or in combination with simethicone may also be used to treat the symptoms of stomach or duodenal ulcers.

With larger doses than those used for the antacid effect, magnesium hydroxide (magnesia) and magnesium oxide antacids produce a laxative effect. The information that follows applies only to their use as an antacid.

Some antacids, like aluminum carbonate and aluminum hydroxide, may be prescribed with a low-phosphate diet to treat hyperphosphatemia (too much phosphate in the blood). Aluminum carbonate and aluminum hydroxide may also be used with a low-phosphate diet to prevent the formation of some kinds of kidney stones. Aluminum hydroxide may also be used for other conditions as determined by your doctor.

These medicines are available without a prescription. However, your doctor may have special instructions on the proper use and dose of these medicines for your medical problem.

Importance of Diet

Make certain your health care professional knows if you are on a low-sodium diet. Some antacids contain large amounts of sodium.

Before using this Medicine


Tell your doctor if you have ever had any unusual or allergic reaction to medicines in this group or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Antacids should not be given to young children (under 6 years of age) unless ordered by their doctor. Since children cannot usually describe their symptoms very well, a doctor should first check the child. The child may have a condition that needs other treatment. If so, antacids will not help and may even cause unwanted effects or make the condition worse. In addition, aluminum- or magnesium-containing medicines should not be given to premature or very young children because they may cause serious side effects, especially when given to children who have kidney disease or who are dehydrated.


Aluminum-containing antacids should not be used by elderly persons with bone problems or with Alzheimer's disease. The aluminum may cause their condition to get worse.


Studies on effects in pregnancy have not been done in either humans or animals. However, there have been reports of antacids causing side effects in babies whose mothers took antacids for a long time, especially in high doses during pregnancy. Also, sodium-containing medicines should be avoided if you tend to retain (keep) body water.

Breast Feeding

Some aluminum-, calcium-, or magnesium-containing antacids may pass into breast milk. However, these medicines have not been reported to cause problems in nursing babies.

Interactions with Medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking any of these medicines, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using medicines in this class with any of the following medicines is not recommended. Your doctor may decide not to treat you with a medication in this class or change some of the other medicines you take.

  • Aclidinium
  • Amantadine
  • Amiloride
  • Amitriptyline
  • Amoxapine
  • Anisotropine
  • Atropine
  • Belladonna
  • Belladonna Alkaloids
  • Benztropine
  • Bepridil
  • Biperiden
  • Bornaprine
  • Brompheniramine
  • Butylscopolamine
  • Canrenoate
  • Canrenone
  • Carbinoxamine
  • Carisoprodol
  • Chlorpheniramine
  • Chlorpromazine
  • Cimetropium
  • Cisapride
  • Clemastine
  • Clidinium
  • Clomipramine
  • Clozapine
  • Cyclobenzaprine
  • Cyclopentolate
  • Cyproheptadine
  • Darifenacin
  • Desipramine
  • Dicyclomine
  • Dimenhydrinate
  • Diphenhydramine
  • Doxepin
  • Dronedarone
  • Emepronium
  • Eplerenone
  • Fesoterodine
  • Flavoxate
  • Fluphenazine
  • Glycopyrrolate
  • Glycopyrronium Tosylate
  • Homatropine
  • Hydroxyzine
  • Hyoscyamine
  • Imipramine
  • Ipratropium
  • Isopropamide
  • Levoketoconazole
  • Loxapine
  • Mebeverine
  • Meclizine
  • Mepenzolate
  • Mesoridazine
  • Methantheline
  • Methixene
  • Methscopolamine
  • Nortriptyline
  • Olanzapine
  • Orphenadrine
  • Oxitropium Bromide
  • Oxybutynin
  • Paroxetine
  • Perphenazine
  • Pimozide
  • Pinaverium
  • Pipenzolate Bromide
  • Piperaquine
  • Pirenzepine
  • Prochlorperazine
  • Procyclidine
  • Promethazine
  • Propantheline
  • Propiverine
  • Protriptyline
  • Quetiapine
  • Revefenacin
  • Saquinavir
  • Scopolamine
  • Solifenacin
  • Sparfloxacin
  • Spironolactone
  • Stramonium
  • Terfenadine
  • Terodiline
  • Thioridazine
  • Thiothixene
  • Tiotropium
  • Tizanidine
  • Tolterodine
  • Triamterene
  • Trifluoperazine
  • Trihexyphenidyl
  • Trimethobenzamide
  • Trimipramine
  • Tropicamide
  • Trospium
  • Umeclidinium
  • Valethamate
  • Ziprasidone

Using medicines in this class with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Acalabrutinib
  • Aceclofenac
  • Acemetacin
  • Alacepril
  • Aliskiren
  • Amiloride
  • Amiodarone
  • Amisulpride
  • Amphetamine
  • Amprenavir
  • Amtolmetin Guacil
  • Anagrelide
  • Apomorphine
  • Aripiprazole
  • Aripiprazole Lauroxil
  • Arsenic Trioxide
  • Aspirin
  • Atazanavir
  • Azilsartan
  • Azilsartan Medoxomil
  • Baloxavir Marboxil
  • Balsalazide
  • Benazepril
  • Benzphetamine
  • Bictegravir
  • Bisacodyl
  • Bromfenac
  • Bufexamac
  • Buprenorphine
  • Bupropion
  • Buserelin
  • Cabotegravir
  • Candesartan
  • Canrenoate
  • Captopril
  • Celecoxib
  • Ceritinib
  • Chloroquine
  • Chlorpromazine
  • Chlortetracycline
  • Choline Magnesium Trisalicylate
  • Choline Salicylate
  • Cilazapril
  • Ciprofloxacin
  • Citalopram
  • Clarithromycin
  • Clofazimine
  • Clonixin
  • Clozapine
  • Crizotinib
  • Dabrafenib
  • Dasatinib
  • Deferasirox
  • Degarelix
  • Delafloxacin
  • Delamanid
  • Delapril
  • Delavirdine
  • Demeclocycline
  • Deslorelin
  • Deutetrabenazine
  • Dexibuprofen
  • Dexketoprofen
  • Dextroamphetamine
  • Diclofenac
  • Diflunisal
  • Digoxin
  • Dipyrone
  • Dolutegravir
  • Domperidone
  • Donepezil
  • Doxycycline
  • Droxicam
  • Efavirenz
  • Eltrombopag
  • Elvitegravir
  • Enalapril
  • Enalaprilat
  • Encorafenib
  • Enoxacin
  • Entrectinib
  • Eprosartan
  • Eravacycline
  • Erdafitinib
  • Erlotinib
  • Escitalopram
  • Etodolac
  • Etofenamate
  • Etoricoxib
  • Felbinac
  • Fenoprofen
  • Fepradinol
  • Feprazone
  • Fexinidazole
  • Fingolimod
  • Floctafenine
  • Fluconazole
  • Flufenamic Acid
  • Fluoxetine
  • Flurbiprofen
  • Formoterol
  • Fosamprenavir
  • Foscarnet
  • Fosinopril
  • Fostemsavir
  • Gatifloxacin
  • Gefitinib
  • Gemifloxacin
  • Glasdegib
  • Gonadorelin
  • Goserelin
  • Grepafloxacin
  • Histrelin
  • Hydroxychloroquine
  • Hydroxyzine
  • Ibuprofen
  • Imidapril
  • Indomethacin
  • Infigratinib
  • Inotuzumab Ozogamicin
  • Irbesartan
  • Iron
  • Ivabradine
  • Ivosidenib
  • Ketoconazole
  • Ketoprofen
  • Ketorolac
  • Ledipasvir
  • Lefamulin
  • Lenvatinib
  • Leuprolide
  • Levofloxacin
  • Levomethadyl
  • Licorice
  • Lisdexamfetamine
  • Lisinopril
  • Lofexidine
  • Lomefloxacin
  • Lornoxicam
  • Losartan
  • Loxoprofen
  • Lumiracoxib
  • Lymecycline
  • Macimorelin
  • Magnesium Salicylate
  • Meclocycline
  • Meclofenamate
  • Mefenamic Acid
  • Meloxicam
  • Memantine
  • Mesalamine
  • Methacycline
  • Methadone
  • Methamphetamine
  • Metronidazole
  • Minocycline
  • Mirtazapine
  • Mobocertinib
  • Moexipril
  • Morniflumate
  • Moxifloxacin
  • Mycophenolate Mofetil
  • Mycophenolic Acid
  • Nabumetone
  • Nafarelin
  • Naproxen
  • Nepafenac
  • Neratinib
  • Niflumic Acid
  • Nimesulide
  • Nimesulide Beta Cyclodextrin
  • Norfloxacin
  • Octreotide
  • Ofloxacin
  • Olmesartan
  • Olsalazine
  • Omadacycline
  • Ondansetron
  • Osilodrostat
  • Osimertinib
  • Oxaliplatin
  • Oxaprozin
  • Oxyphenbutazone
  • Oxytetracycline
  • Ozanimod
  • Pacritinib
  • Panobinostat
  • Parecoxib
  • Pasireotide
  • Pazopanib
  • Penicillamine
  • Pentopril
  • Perindopril
  • Phenylbutazone
  • Phenyl Salicylate
  • Phenytoin
  • Piketoprofen
  • Pimavanserin
  • Piroxicam
  • Pitolisant
  • Ponesimod
  • Posaconazole
  • Pranoprofen
  • Proglumetacin
  • Propyphenazone
  • Proquazone
  • Quetiapine
  • Quinapril
  • Quinine
  • Raltegravir
  • Ramipril
  • Ribociclib
  • Rilpivirine
  • Rofecoxib
  • Rolitetracycline
  • Salicylamide
  • Salicylic Acid
  • Salsalate
  • Sarecycline
  • Secretin Human
  • Selpercatinib
  • Senna
  • Sertraline
  • Sevoflurane
  • Siponimod
  • Sodium Picosulfate
  • Sodium Polystyrene Sulfonate
  • Sodium Salicylate
  • Solifenacin
  • Sotalol
  • Sotorasib
  • Sparfloxacin
  • Spirapril
  • Spironolactone
  • Sulfasalazine
  • Sulindac
  • Sulpiride
  • Sunitinib
  • Tacrolimus
  • Telmisartan
  • Temocapril
  • Tenoxicam
  • Tetracycline
  • Tiaprofenic Acid
  • Tigecycline
  • Tizanidine
  • Tolazoline
  • Tolfenamic Acid
  • Tolmetin
  • Trandolapril
  • Trazodone
  • Triamterene
  • Triclabendazole
  • Triptorelin
  • Trolamine Salicylate
  • Trovafloxacin
  • Valdecoxib
  • Valsartan
  • Vandetanib
  • Vemurafenib
  • Vinflunine
  • Vismodegib
  • Voclosporin
  • Zofenopril
  • Zuclopenthixol

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of medicines in this class. Make sure you tell your doctor if you have any other medical problems, especially:

  • Alzheimer's disease (for aluminum-containing antacids only) or
  • Appendicitis (or signs of) or
  • Bone fractures or
  • Colitis or
  • Constipation (severe and continuing) or
  • Hemorrhoids or
  • Intestinal blockage or
  • Intestinal or rectal bleeding—Antacids may make these conditions worse
  • Colostomy or
  • Ileostomy or
  • Inflamed bowel—Use of antacids may cause the body to retain (keep) water and electrolytes such as sodium and/or potassium
  • Edema (swelling of feet or lower legs) or
  • Heart disease or
  • Liver disease or
  • Toxemia of pregnancy—Use of sodium-containing antacids may cause the body to retain (keep) water
  • Kidney disease—Antacids may cause higher blood levels of aluminum, calcium, or magnesium, which may increase the risk of serious side effects
  • Sarcoidosis—Use of calcium-containing antacids may cause kidney problems or too much calcium in the blood
  • Underactive parathyroid glands—Use with calcium-containing antacids may cause too much calcium in the blood

Proper use of this Medicine

For patients taking the chewable tablet form of this medicine:

  • Chew the tablets well before swallowing. This is to allow the medicine to work faster and be more effective.

For patients taking this medicine for a stomach or duodenal ulcer:

  • Take it exactly as directed and for the full time of treatment as ordered by your doctor, to obtain maximum relief of your symptoms.
  • Take it 1 and 3 hours after meals and at bedtime for best results, unless otherwise directed by your doctor.

For patients taking aluminum carbonate or aluminum hydroxide to prevent kidney stones:

  • Drink plenty of fluids for best results, unless otherwise directed by your doctor.

For patients taking aluminum carbonate or aluminum hydroxide for hyperphosphatemia (too much phosphate in the blood):

  • Your doctor may want you to follow a low-phosphate diet. If you have any questions about this, check with your doctor.


The dose medicines in this class will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


Keep out of the reach of children.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Do not keep outdated medicine or medicine no longer needed.

Precautions while using this Medicine

If this medicine has been ordered by your doctor and you will be taking it in large doses, or for a long time, your doctor should check your progress at regular visits. This is to make sure the medicine does not cause unwanted effects.

Some tests may be affected by this medicine. Tell the doctor in charge that you are taking this medicine before you have any tests to determine how much acid your stomach produces.

Do not take this medicine:

  • if you have any signs of appendicitis or inflamed bowel (such as stomach or lower abdominal pain, cramping, bloating, soreness, nausea, or vomiting). Instead, check with your doctor as soon as possible.
  • within 1 to 2 hours or more of taking other medicine by mouth. To do so may keep the other medicine from working properly.

For patients on a sodium-restricted diet:

  • Some antacids (especially those containing sodium bicarbonate) contain a large amount of sodium. If you have any questions about this, check with your health care professional.

For patients taking this medicine for increased stomach acid:

  • Do not take it for more than 2 weeks unless otherwise directed by your doctor. Antacids should be used only for occasional relief.
  • If your stomach problem is not helped by the antacid or if it keeps coming back, check with your doctor.
  • Using magnesium- or sodium bicarbonate-containing antacids too often, or in high doses, may produce a laxative effect. This happens fairly often and depends on the individual's sensitivity to the medicine.

For patients taking aluminum-containing antacids (including magaldrate):

  • Before you have any test in which a radiopharmaceutical will be used, tell the doctor in charge that you are taking this medicine. The results of the test may be affected by aluminum-containing antacids.

For patients taking calcium- or sodium bicarbonate-containing antacids

  • Do not take the antacid with large amounts of milk or milk products. To do so may increase the chance of side effects.

Side Effects of this Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Along with its needed effects, a medicine may cause some unwanted effects. Although the following side effects occur very rarely when this medicine is taken as recommended, they may be more likely to occur if: too much medicine is taken; it is taken in large doses; it is taken for a long time; or it is taken by patients with kidney disease.

Check with your doctor as soon as possible if any of the following side effects occur:

For aluminum-containing antacids (including magaldrate)

  • Bone pain
  • constipation (severe and continuing)
  • feeling of discomfort (continuing)
  • loss of appetite (continuing)
  • mood or mental changes
  • muscle weakness
  • swelling of wrists or ankles
  • weight loss (unusual)

For calcium-containing antacids

  • Constipation (severe and continuing)
  • difficult or painful urination
  • frequent urge to urinate
  • headache (continuing)
  • loss of appetite (continuing)
  • mood or mental changes
  • muscle pain or twitching
  • nausea or vomiting
  • nervousness or restlessness
  • slow breathing
  • unpleasant taste
  • unusual tiredness or weakness

For magnesium-containing antacids (including magaldrate)

  • Difficult or painful urination (with magnesium trisilicate)
  • dizziness or lightheadedness
  • feeling of discomfort (continuing)
  • irregular heartbeat
  • loss of appetite (continuing)
  • mood or mental changes
  • muscle weakness
  • unusual tiredness or weakness
  • weight loss (unusual)

For sodium bicarbonate-containing antacids

  • Frequent urge to urinate
  • headache (continuing)
  • loss of appetite (continuing)
  • muscle pain or twitching
  • nausea or vomiting
  • nervousness or restlessness
  • slow breathing
  • swelling of feet or lower legs
  • unpleasant taste
  • unusual tiredness or weakness

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Chalky taste

Less common

  • Constipation (mild)
  • diarrhea or laxative effect
  • increased thirst
  • speckling or whitish discoloration of stools
  • stomach cramps

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

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Further information

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