What Are Antibiotics and How Do They Work?

Antibiotics are medicines used to treat certain infections caused by bacteria. They have transformed modern healthcare by making many previously dangerous bacterial infections much easier to treat.

However, antibiotics don't work against every infection. Understanding what antibiotics do, when they are useful, and how to use them correctly is important for protecting your health and reducing antibiotic resistance.

What Are Antibiotics?

Antibiotics are medicines designed to kill bacteria or stop them from growing and multiplying.

They are used to treat certain bacterial infections, such as some urinary tract infections, bacterial skin infections, and certain respiratory infections.

Different antibiotics work against different types of bacteria, which is why the appropriate medicine depends on the infection and the bacteria involved.

How Do Antibiotics Work?

Antibiotics work in different ways depending on the specific medicine.

Some antibiotics damage the protective structures surrounding bacterial cells. Others interfere with the bacteria's ability to produce proteins, copy their genetic material, or carry out other processes necessary for survival.

The result is either that the bacteria are killed or that they can no longer multiply effectively, allowing the body's immune system to help clear the infection.

Do Antibiotics Kill Viruses?

No.

This is one of the most important things to understand about antibiotics.

Antibiotics work against bacteria, not viruses.

Common viral infections such as most colds and many cases of flu do not improve because someone takes an antibiotic. Taking antibiotics unnecessarily exposes you to potential side effects without treating the underlying viral infection.

Why Doesn't Every Infection Need Antibiotics?

Many common infections are caused by viruses and improve on their own with time and supportive care.

Even when an infection is bacterial, an antibiotic may not always be necessary. A healthcare professional needs to consider the type and severity of the infection before deciding whether antibiotics are appropriate.

This is why you shouldn't automatically ask for antibiotics whenever you feel unwell.

How Are Antibiotics Taken?

Antibiotics come in different forms, including:

• Tablets and capsules.
• Liquids.
• Creams and ointments.
• Injections or intravenous medicines.
• Other specialised formulations.

The correct form, dose, and duration depend on the medicine and the infection being treated.

Always follow the instructions given by your doctor or pharmacist.

Why Is It Important to Take Antibiotics Correctly?

Using antibiotics incorrectly can cause problems.

Taking the wrong dose, taking them at the wrong times, sharing them with someone else, or using leftover antibiotics can all be unsafe.

If you have been prescribed an antibiotic, use it exactly as directed and speak with your healthcare professional if you have questions or concerns.

Don't change your treatment on your own.

What Is Antibiotic Resistance?

Antibiotic resistance occurs when bacteria change in ways that allow them to survive medicines that would normally kill them or stop their growth.

When resistant bacteria spread, infections can become more difficult to treat.

This is a major reason why antibiotics should only be used when they are medically appropriate.

How Does Antibiotic Resistance Develop?

Bacteria can develop resistance through genetic changes. The use and misuse of antibiotics can give resistant bacteria an advantage, allowing them to survive while susceptible bacteria are eliminated.

Resistance can become more likely when antibiotics are used unnecessarily or incorrectly.

This is why responsible antibiotic use matters not only for you but also for the wider community.

Can You Take Someone Else's Antibiotics?

No.

You should not take antibiotics prescribed for another person, even if their symptoms seem similar to yours.

Different infections can require different treatments, and an antibiotic that is appropriate for one person may be inappropriate for another.

If you are unwell, speak with a doctor or pharmacist about your symptoms.

Can You Use Leftover Antibiotics?

It's best not to keep leftover antibiotics for future illnesses.

The medicine may not be appropriate for your next infection, and using an incomplete or unsuitable treatment can contribute to medication problems and antibiotic resistance.

If you have unused antibiotics at home, ask a pharmacist about safe disposal rather than saving them for later.

What Are the Side Effects of Antibiotics?

Like all medicines, antibiotics can cause side effects.

Depending on the antibiotic, these may include:

• Nausea.
• Diarrhoea.
• Stomach discomfort.
• Skin rash.
• Headache.

Some people can experience serious allergic reactions or other significant side effects.

If you develop severe symptoms such as difficulty breathing, swelling of the face or throat, or loss of consciousness after taking an antibiotic, seek urgent medical attention.

Can Antibiotics Affect Good Bacteria?

Yes.

Antibiotics can affect some of the bacteria that normally live in the body, including beneficial bacteria in the digestive system.

This can sometimes contribute to digestive symptoms such as diarrhoea.

The effects vary depending on the antibiotic and the individual.

Can Antibiotics Be Taken With Other Medicines?

Some antibiotics can interact with other medicines, supplements, foods, or substances.

That's why it's important to tell your doctor or pharmacist about everything you're currently taking before starting an antibiotic.

This includes prescription medicines, over-the-counter products, vitamins, and supplements.

What If You Forget a Dose?

The correct response to a missed dose depends on the specific antibiotic.

Check the instructions provided with your medicine or ask your pharmacist what to do.

Do not automatically take a double dose to make up for a missed one unless a healthcare professional specifically tells you to.

Should You Stop Antibiotics When You Feel Better?

Don't make changes to your antibiotic treatment without speaking with your healthcare professional.

The appropriate duration of treatment depends on the infection and the specific antibiotic. If you're experiencing side effects or have concerns about continuing the medicine, contact your doctor or pharmacist for advice.

How Can You Use Antibiotics Responsibly?

You can help protect yourself and others by:

• Only using antibiotics when appropriately prescribed or recommended.
• Never sharing antibiotics.
• Not using leftover antibiotics.
• Following the prescribed instructions.
• Taking the correct dose.
• Asking questions when you're unsure.
• Avoiding antibiotics for illnesses they cannot treat.

Responsible use helps preserve the effectiveness of antibiotics for people who genuinely need them.

Ask Your Pharmacist About Antibiotics

If you've been prescribed an antibiotic or have questions about one, your pharmacist can explain how to use it correctly.

You can ask about:

How should I take it?

Should I take it with food?

What side effects should I watch for?

Can I take it with my other medicines?

What should I do if I miss a dose?

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Final Thoughts

Antibiotics are powerful medicines that can save lives when used appropriately. They work against bacteria by killing them or stopping them from growing and multiplying.

But they are not a cure for every infection. They don't treat viral illnesses such as most colds and flu, and unnecessary use can contribute to antibiotic resistance.

If you think you have an infection, don't simply take an antibiotic because it worked for someone else. Get appropriate medical advice and use antibiotics exactly as directed.

For more practical medicine guides, healthcare information, and wellness advice, read more on the Meddylab blog.

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