According to the Australian Museum, more than 250 people are given antivenom each year, with several milder instances probably going unreported. Bites cause pain, sweating, muscular weakness, nausea and vomiting, but serious illness does not develop for at least three hours, allowing victims time to seek medical attention.

NSW Health says redback spider bites are common but very unlikely to prove lethal, even if untreated. They can result in severe pain and symptoms that can continue from hours to days.

The initial bite may only cause mild discomfort or irritation, and sometimes is not even noticed.

Pain usually increases over an hour or two and may radiate up the limb. Abdominal or chest pain may develop, as may pain in other parts of the body.

The pain is persistent and usually severe enough to interfere with normal activities, such as work or sleep.

The duration of effects vary, with only moderate pain for a few hours in some cases, to severe persistent pain for two to five days.