9 biggest questions about antibiotics, answered

Hailed as ‘miracle drugs’, the discovery of antibiotics revolutionised modern medicine. But as overuse dulls their once-magical powers, here’s what you need to know.

Most of us have had a course of antibiotics at one time or another.

Scottish physician Sir Alexander Fleming observed the bacterial-killing effects of penicillin in his London lab back in 1928.

“Before his discovery, the life expectancy of adults in the 19th century was around 50 years, with this primarily due to infectious diseases,” Dr Isabelle Carr tells House of Wellness TV.

While they have saved countless lives, using them can also contribute to antibiotic resistance – one of the most urgent threats to public health, according to the World Health Organisation.

“Bacteria are very clever little organisms and when we started using antibiotics widely, both in farming and medicine, they began to change and adapt,” Dr Carr says.

“Nowadays there are bacteria that are virtually resistant to all the antibiotics we have, which is pretty scary.”

Her dad, Dr Nick Carr, tells House of Wellness TV that it’s important to only take antibiotics when we really need them.

So what else do you need to know about antibiotics?

How do antibiotics work?

“Antibiotics work by killing bacteria or stopping them from multiplying,” Melbourne Medical School academic GP Dr Jo-Anne Manski-Nankervis says.

“These work alongside the body’s natural immune system, which is also busy fighting off the infection. Different antibiotics work against different types of bacteria.”

When should you take antibiotics?

Our bodies do a really good job of combating some infections all by themselves, Dr Manski-Nankervis reveals.

“Other times it’s clear they need a bit of help, so it’s important you see you GP to get a proper assessment if you’re concerned,” she says.

What are the most common antibiotics?

Some of the most common antibiotics are amoxicillin (used to treat ear infections), cephalexin (often used for skin infections) and trimethoprim (bladder infections).

Do antibiotics kill viruses?

“Antibiotics only work with bacterial infections,” says Dr Nick Carr.

“Virus infections — the minor ones, like common colds and coughs, or the nasty ones like HIV and COVID-19 — don’t respond to antibiotics.”

Can you take antibiotics during pregnancy?

“Yes, you can,” Dr Manski-Nankervis says.

“As doctors we have access to lots of databases to ensure the antibiotics we prescribe are safe for both the woman and her baby during pregnancy and breastfeeding. It’s important to disclose if you think you might be pregnant.”

Can you drink alcohol while taking antibiotics?

Not the best idea, says Dr Manski-Nankervis.

“Some people get tummy disturbances with antibiotics and alcohol isn’t going to help. Also, you’re usually taking antibiotics when you’re sick, so alcohol is going to leave you feeling dehydrated and worse all round,” she says.

Do antibiotics give you thrush?

Yes. “Antibiotics don’t just kill the bacteria causing the infection but can also kill the beneficial bacteria that prevent the overgrowth of yeast which can lead to thrush,” Dr Manski-Nankervis says.

“It’s usually easy to treat so speak to your health practitioner.”

Do antibiotics make you tired?

If you’re sick you’re usually feeling tired because your body is busy fighting the infection, so it’s often the infection causing the tiredness, describes Dr Manski-Nankervis.

“But tiredness is noted as a potential side effect of some antibiotics,” she says. “Resting and keeping hydrated is good advice.”

What are the side effects of antibiotics?

Common side effects include diarrhoea, nausea, stomach pain and sometimes skin rashes.

“A rash doesn’t necessarily mean you have an allergy, you might just be intolerant — it’s an important differentiation and might be worth exploring so you’re not doing yourself out of an effective antibiotic,” Dr Manski-Nankervis cautions.

Where to get more information

The Australian Commission on Safety and Quality in Healthcare and the National Centre for Antimicrobial Stewardship both have handy info sheets about antibiotics.

More health and immunity advice

Written by Liz McGrath.