Can I take leftover antibiotics from before?

Q: Can I take leftover antibiotics from before?

Taking leftover antibiotics is not safe. Here's why: - **They may not treat your current illness.** Antibiotics are prescribed for specific bacterial infections. The leftover medication may be the wrong type, or your symptoms may be caused by a virus, which antibiotics cannot treat. - **Incorrect use fuels antibiotic resistance.** Taking the wrong antibiotic, or an incomplete dose, allows bacteria to adapt and survive, making future infections harder to treat. - **The dose or duration may be inadequate.** Leftover supplies are, by definition, incomplete, and partial treatment can worsen your condition. If you're feeling unwell and unsure what to do next, guessing with old medication is risky. A free, instant, and private online symptom check can help you understand what may be causing your symptoms and guide you toward the right next steps — whether that's home care, seeing a doctor, or seeking urgent help. It takes just a few minutes and could save you from a serious misstep. Reviewed for medical accuracy: 07/15/2026

Reviewed by Yoshinori Abe, MD

Internal Medicine

Taking leftover antibiotics is not safe. Here's why:

They may not treat your current illness. Antibiotics are prescribed for specific bacterial infections. The leftover medication may be the wrong type, or your symptoms may be caused by a virus, which antibiotics cannot treat.
Incorrect use fuels antibiotic resistance. Taking the wrong antibiotic, or an incomplete dose, allows bacteria to adapt and survive, making future infections harder to treat.
The dose or duration may be inadequate. Leftover supplies are, by definition, incomplete, and partial treatment can worsen your condition.

If you're feeling unwell and unsure what to do next, guessing with old medication is risky. A free, instant, and private online symptom check can help you understand what may be causing your symptoms and guide you toward the right next steps — whether that's home care, seeing a doctor, or seeking urgent help. It takes just a few minutes and could save you from a serious misstep.

Reviewed for medical accuracy: 07/15/2026

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Explanation

Taking leftover antibiotics is not a good idea. According to studies, many people keep leftover antibiotics and use them without a doctor's advice. This can be harmful because the leftover antibiotics might not be the right type or dose for your current illness. Also, using antibiotics when they are not needed can lead to antibiotic resistance, which means that the medicine might not work when you really need it.

Here are some important points to remember:

Right Medicine: Antibiotics are made to treat specific bacterial infections. If you use the wrong one, it might not help and could make things worse.
Resistance Risk: Taking antibiotics when not needed can make bacteria stronger and harder to kill.
Doctor's Guidance: Always talk to a doctor before taking antibiotics to make sure you get the right treatment.

Remember, it is important to finish all prescribed antibiotics when they are given to you, and never save them for later. If you're feeling unwell and unsure whether you need medical attention, try our free symptom checker to help guide your next steps in getting the right care.

(References)

Shah J, Trautner BW, Olmeda K, Laytner LA, Faustinella F, Paasche-Orlow MK, & Grigoryan L. (2024). A survey of patient practices regarding leftover antibiotics .... Antimicrobial agents and chemotherapy, 38975752.
Al-Mehmadi B, Alsubaie S, Al-Morikhi O, Alqahtani F, Almutairi W, Al-Mutairi M, et al. (2023). Knowledge and Attitude of self-medication with leftover .... F1000Research, 39618514.
Kardas P, Pechère JC, Hughes DA, & Cornaglia G. (2007). A global survey of antibiotic leftovers in the outpatient setting. International journal of antimicrobial agents, 17933498.

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