Drug Interactions with Antacids

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What are Antacids and what are they used for?

Antacids are medicines that neutralize stomach acid. Antacids are used to relieve acid indigestion, upset stomach, sour stomach, and heartburn. Additional components of some formulations include simethicone, to reduce gas pains (flatulence) and alginic acid, which, in combination with antacids, may help manage GERD (gastro-esophageal reflux disease). Antacids should not be confused with gastric acid inhibitors, such as the H-2 receptor blockers (cimetidine, ranitide and others) or the proton pump inhibitors (lansoprazole, omeprazole and others). Although all three classes of drugs act to reduce the levels of gastric acid, their mechanisms are different, and this affects the appropriate use of the drug. Antacids have a rapid onset and short duration of action, and are most appropriate for rapid relief of gastric discomfort for a short period of time.

 Antacids may be divided into two classes:

1.Those that work by chemical neutralization of gastric acid (like sodium bicarbonate) and

2.Those that act by adsorption of the acid (non-absorbable antacids), such as calcium and magnesium salts.

Chemical antacids (like simethicone and alginic acid) show the most rapid onset of action, but may cause "acid rebound," a condition in which the gastric acid returns in greater concentration after the drug effect has stopped . And since these antacids may contain high concentrations of sodium, they may be inappropriate in patients with hypertension.

Drug interactions with Antacids:

Antacids have multiple drug interactions, usually due to inhibition of absorption of other medications. In rare cases, the absorbable antacids may alter the pH of the stomach contents or urine sufficiently to alter drug absorption or excretion. The interactions can be avoided by taking these other drugs one hour before or three hours after the antacid.

Some herbs and supplements that interact with antacids:

Acidophilus and Ginger; antacids affect their absorption.


Drugs less absorbed when taking antacids include:

 Tetracycline, Antifungals (Sporonox), Ciprofloxacin (Cipro), Propranolol (Inderal), Captopril (Capoten), Ranitidine (Zantac), Famotidine (Pepcid AC), Allegra (Fexofenadine is the scientific name of this antihistamine), Quinolone antibiotics and iron supplements.

Antacids can also potentiate (make stronger) the following drugs:

- Valproic acid: Used to treat epilepsy, bipolar disease and migraines.

- Sulfonylureas:Drugs used to treat Type II diabetes including: Amaryl,Glyburide, Glucotrol, Chlorpropamide, Diabinese, Tolazamide, Tolinase Acetohexamide, Glipizide, Tolbutamide, Orinase, Glimepiride, Diabeta, Micronase, Glubenclamide and Gliclazide.

- Quinidine: cardiac drug (trade names Quinidex and Quinora) used to  treat certain heart arrhythmias.
- Levodopa: and anti-Parkinson’s drug.

- Dixoxin/Lanoxin: heart drugs used in treating congestive heart  failure.


Recommended dosage:

The dose depends on the type of antacid.

When using antacids in chewable tablet form, chew the tablet well   before swallowing. Drink a glass of water after taking chewable aluminum hydroxide. Lozenges should be allowed to dissolve completely in the mouth. Liquid antacids should be shaken well before using.


Antacids have multiple drug interactions, usually due to inhibition of absorption of other medications. In rare cases, the absorbable antacids may alter the pH of the stomach contents or urine sufficiently to alter drug absoprtion or excretion. Also, many precautions must be taken in antacid administration during pregnancy and breastfeeding. antacids have a no. offside effects and must not be used regularly.thus, being cautious will lead us to better drug effects in our body.


About the Author

Juhis's picture
Author: Juhis

There are 12 Comments

kranthi kumar's picture

Dear Juhi sharma,
Good start up, its interesting to learn that antacids are used to relieve acid indigestion, upset stomach, sour stomach, and heartburn etc.
The affect on drug intraction is also good.
Can you give me some side effects associated with over use of antacids ?? Will this damage liver ??
Why a perosn has to Drink a glass of water after taking chewable aluminum hydroxide ??

" "


Juhis's picture

potentiate problems assocated with overdose of antacids are poor digestion,absorbtion,increased food allergies,bloating,git infections,phosphate depletion,inc. risk of rickets etc.

aluminium containing antacids include side effects like diarrheoea,constipation and hence adviced to take water.

Juhi Sharma
Team Infinity

Sai's picture

Good job Juhi... I am just wondering does Simethicone neutralizes acid ? I thought it is s an antiflatulent and usually coalesce the smaller gas bubbles into larger bubbles, thereby easing the release of gas within the GIT via burping or flatulence ..

Juhis's picture

simithecone does not neutralizes acids.it is a spreading agent added to disperse foam by encouraging bubbles to join together, thereby making it easier for them to be brought up with a burp. Simethicone has no significant effect on gas in the intestines.

Juhi Sharma
Team Infinity

Zarrin Faria's picture

Great information on anta-acids ...can by any mechanism like adding some adittives or excipient or in combination with any other drug molecules can the rebound effect produced by the chemical antacids be reduced or eliminated??? Is there any further scope of research in this area???
Faria Zarrin
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Eswar GsnkRao's picture

Dear Juhi Sharma,
Nicely explained,
After knowing the problems of co-adminsitration of them with other drugs, If a patient needs to take both types of agents then what to do?
Suggest simple ways to follow......
eswar :-)


ESWAR :-) 

Sowmya Bharadwaj's picture

Dear Juhi,

Nice information....

But can u plz give me the information regarding the selection of antacids??? and their action on neutralization of stomach pH??


Gupta Shubhranshu's picture

Nice blog juhi...by the way, what are ur views about ADR with macrolides, especially with azithromycin... Because there have been few controversial reports available regarding its altered bioavailability on concurrent oral administration with antacids...