Quick answer

Ask your pharmacist or doctor before combining. NIH says antibiotic and antifungal medicines might make some probiotics less effective, and antibiotics can kill helpful bacteria in the digestive tract. NIH gives no schedule for taking the two, so ask your pharmacist how to fit a probiotic around your antibiotic.^1,2,3

Key facts

NIH's fact sheets on immune function say antibiotic and antifungal medicines might decrease the effectiveness of some probiotics.^1,4
NIH's consumer fact sheet says antibiotics, such as erythromycin and penicillin, can kill beneficial microorganisms in the digestive tract, which sometimes results in diarrhea.²
The amoxicillin label says antibacterial treatment alters the normal flora of the colon, and watery or bloody stools can begin even 2 or more months after the last dose.³
NIH names no spacing between a probiotic and an antibiotic, and its health professional fact sheet says the results of probiotic research depend on the antibiotic, the strain and the person.⁵

Ask your pharmacist or doctor first

Antibiotics can kill helpful bacteria in the digestive tract, and NIH says antibiotic and antifungal medicines might make some probiotics less effective. Ask your pharmacist how to time a probiotic around your medicine, and keep taking the antibiotic exactly as prescribed.^1,2,3,4

Expected from how the two work, not shown in studies

What is documented

Ask your pharmacist or doctor first

Expected from how the two work, not shown in studies

NIH's health professional fact sheet on immune function states that probiotics are not known to interact with medications, apart from this one point: antibiotic and antifungal medications might decrease the effectiveness of some probiotics. Its consumer version repeats it. The wording covers antibiotics as a group and does not name a specific antibiotic or a specific probiotic.^1,4

Why antibiotics and probiotics come up together

Antibiotics act on bacteria, and that includes helpful ones in the gut. NIH says they can kill beneficial microorganisms in the digestive tract, which sometimes results in diarrhea. Its health professional sheet adds that up to 30 percent of people who use antibiotics have diarrhea, and that some antibiotics, such as erythromycin and penicillin, are linked to it more often.^2,5

The amoxicillin label describes the same effect from the antibiotic's side. It says antibacterial treatment alters the normal flora of the colon, and that watery and bloody stools can begin even 2 or more months after the last dose. It tells you to contact your doctor if they do, and to take the doses exactly as directed.³

Watery or bloody stools during or after an antibiotic course call for a call to your doctor. A probiotic is not a substitute for that call, and NCCIH advises against using one as a reason to postpone seeing a provider.^3,6

What the sources leave open

Researchers have tested probiotics given during antibiotic courses. NIH says the results depend on the type of antibiotic, the probiotic strain, the life stage of the person and whether they are in hospital or at home, and NCCIH says that even for the conditions studied most, it is still not known which probiotics are helpful or how much to take. This page does not repeat those results, because it is about combining the two and not about whether a probiotic is worth taking.^5,6

No source we read gives a time gap between a dose of a probiotic and a dose of an antibiotic, so this page does not either. Any schedule you hear should come from your pharmacist, who can see which antibiotic and which probiotic you take.^1,5

Which antibiotic you take

The NIH statement covers antibiotics as a group, so it applies in the same way whether yours is amoxicillin, doxycycline, a cephalosporin or another kind. The one label we read, for amoxicillin, speaks about the colon's normal flora and not about probiotics, and we found no official source that names a probiotic with doxycycline or amoxicillin.^1,3

Check the label of the whole probiotic product too. A capsule may hold other ingredients, and your pharmacist can check them against your antibiotic.²

Who should be extra careful

At least 60 reports since 1966 have linked probiotics containing the yeast Saccharomyces to fungal bloodstream infections. Many of the patients were in intensive care, were fed by tube or vein, had a central venous catheter or had received broad-spectrum antibiotics.⁵

Rare serious illness from probiotics has been reported mostly in people who were severely ill or had weakened immune systems, and many of the yeast cases involved people who had received broad-spectrum antibiotics. If you are in hospital, seriously ill or have a weakened immune system, ask your doctor before taking any probiotic with an antibiotic.^5,6

NCCIH also lists the transfer of antibiotic resistance genes from probiotic microorganisms to other gut microbes among possible harms of probiotics. It is a reason to mention a probiotic to your pharmacist.⁶

Do not give a probiotic supplement to a premature baby. FDA warned in 2023 of severe, potentially fatal infection in preterm infants given probiotics, and it has approved no probiotic as a drug for infants of any age.⁷

What to ask your pharmacist

Is a probiotic worth adding for my antibiotic and my situation, and which strain do you advise?
How should I fit it around my doses, and how long should I keep taking it after the course ends?
Does my probiotic product contain anything else that matters with my antibiotic?
Which stool changes mean I should call you or my doctor?

Bring the Supplement Facts panel of the probiotic, and the name of your antibiotic. Keep taking the antibiotic exactly as prescribed.³

Questions people ask

Can I take probiotics with amoxicillin?

Ask your pharmacist. NIH covers antibiotics as a group and does not name amoxicillin, and the amoxicillin label we read does not mention probiotics. Keep taking the antibiotic exactly as directed.^1,3

Can I take probiotics and doxycycline at the same time?

We found no official source that addresses a probiotic with doxycycline, and none that gives a time gap for any antibiotic. Ask your pharmacist.¹

How much probiotic should I take while on antibiotics?

There is no official amount. NIH says there are no recommendations for healthy people and suggests asking a provider which probiotic to choose, what dose and how long to use it.²

Do I need a probiotic after an antibiotic course?

There is no official recommendation either way for healthy people. Watery or bloody stools can begin even 2 or more months after the last dose and call for contacting a doctor.^3,5

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Sources

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.