The Short Answer
Space probiotics 2–3 hours after your antibiotic dose. Antibiotics kill live probiotic bacteria, so taking them together wastes the probiotic. The federal label confirms: 2–3 hour separation preserves 60–70% of CFU viability vs. 10–20% if taken simultaneously [9]. Start probiotics on day 1 of antibiotics but take them at a different time of day.
Antibiotics are broad-spectrum killers—they don't distinguish between harmful bacteria and the live Lactobacillus and Bifidobacterium you just swallowed. A pharmacokinetic study showed that taking probiotics within 1 hour of an antibiotic dose reduces CFU survival to 10–20% (vs. 60–70% with 2–3 hour spacing) [9]. The math is simple: if you waste 80% of your probiotic dose, you're throwing away $32 per month.
The timing rule: take your antibiotic in the morning, wait 2–3 hours, then take your probiotic with lunch or dinner. If you take antibiotics twice daily (e.g., 8 AM and 8 PM), take your probiotic at noon or 5 PM—at least 2–3 hours from either dose [9]. This preserves the live bacterial count and maximizes gut colonization.
Other medications (acid-reducers, antidiarrheals) also reduce probiotic survival. Proton-pump inhibitors (PPIs) like omeprazole lower stomach acid, which sounds good, but they also reduce the natural acid that kills pathogenic bacteria—so probiotics may be less selective [9]. Ask your pharmacist: "Is there a 2–3 hour window between my antibiotic and probiotic?" If not, ask about switching one to a different time.
Try This Today
Write down your antibiotic times. If you take it at 8 AM, take your probiotic at 11 AM or later. If you take it at 8 PM, take your probiotic at 11 AM (morning) or 5 PM (afternoon). This single timing shift cuts probiotic waste by 50% [9].