Can You Take Antacids With Your Antibiotic?

In our latest question and answer, the pharmacist discusses why taking antacid products with your antibiotic can result in a significant interaction.

Dec 29, 2017

sugar plum asked

I have been told to take amoxicillin 3 times a day for a chest infection. This is the 5th round of antibiotics and the infection has never cleared. I take Gaviscon liquid for heart burn quite often at the same time as my antibiotic. Should I stop taking the Gaviscon or not have it at the same time?


It is generally recommended not to combine antacid medications (e.g. Gaviscon, Maalox, Tums) with antibiotics. These products interact with many antibiotic medications, making them less effective and potentially causing treatment failure.

The antacids of concern are ones that contains any of the following ingredients:

  • Calcium Carbonate
  • Aluminum Hydroxide
  • Magnesium Carbonate

Calcium, aluminum and magnesium are well known to combine, or 'chelate' with many antibiotic medications. Chelation simply refers to a metal ion/compound (e.g. calcium) binding to a non-metal ion/compound (e.g. an antibiotic). Once an antibiotic is chelated, the oral absorption of the product is often significantly reduced, resulting in reduced antibiotic concentrations in the blood. This has to potential to cause a situation where you do not absorb a dose large enough to be effective in eradicating your infection.

It's not just the metals in antacids that can affect your medication but foods that contain calcium, aluminum or magnesium can as weell. This is why many medication labels will indicate that they should not be taken with dairy or other calcium containing foods.

If you are taking an antibiotic that is known to interact with the compounds mentioned above, it is generally recommended that the antibiotic should be taken either 2 hours before or 6 hours after taking the potentially interacting agent. 

If you have been consuming the antacid Gaviscon, which contains aluminum and magnesium, there is a good chance it has been binding with your antibiotic medications, making them less effective. Below, are some common medication classes known to interact with calcium, aluminum and magnesium:

Calcium, Magnesium, Aluminum Interaction With Antibiotic Class:
  • Tetracyclines (e.g. tetracycline, doxycycline)
  • Fluoroquinolones (e.g. Levaquin, ciprofloxacin)
  • Macrolides (e.g. azithromycin)

It should be noted that not all antacids contain calcium, magnesium or aluminum. H2 blockers, like Zantac (ranitidine) and Pepcid (famotidine), as well as PPI drugs, like Prilosec (omeprazole) and Prevacid (lansoprazole), do not contain those interacting ingredients.

Please be sure to speak with your doctor/pharmacist regarding all the medications you take to avoid any additional interactions.

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