The Redback Spider Bite: Are Some People Immune?

A couple months ago I did an interview with Professor Julian White (MB, BS, MD, FACTM), Consultant Clinical Toxinologist and Head of Toxinology at the Women’s & Children’s Hospital, Adelaide. We discussed Redback Spider Antivenom Doesn’t Work; True or False?

As some of you will know, I was bitten by redback spider and when I telephoned my doctor I was told not to panic, only a small minority of bites cause a reaction that needs medical intervention.

Spider, Australian Red-back,  female spiderIn my case I was lucky, I suffered no adverse reactions and by the next day it was as if it had never happened. Any of you who have read my post What It’s Really Like to Be Bitten by a Redback Spider and in particular all the comments below it will know that for many people the reactions can be quite severe.

After I’d finished my interview with Professor White, quite a while after, I found myself kicking myself, not literally though, that would be silly. I hadn’t asked one of the most important questions of all, a question that has also been debated in the comments without ever reaching a definitive conclusion.

I really needed to get back to Julian but that wasn’t easy, I had been speaking to him through a media agency and he’s a busy man. Fortunately I know Geoff Coombe, my snake expert and he knows Julian, they’ve worked together. I asked Geoff, Geoff asked Julian, and Bobs your uncle. Here’s the answer, but first…

What is the Question?

Are some people naturally more inclined to react to a redback spider bite whilst others show less of a reaction simply because of biology, or is the reaction caused by a redback spider bite directly related to the amount of venom injected by the spider?

You know how some people are allergic to wasp stings? Are some people simply allergic to the redback spider and for everyone else it is just painful and then it goes away?

So, is it the amount of venom, or the person?

Over to Professor Julian White for this most comprehensive answer:

Professor Julian White

Professor Julian White

“A number of factors affect how a particular person reacts to a red back spider bite;

  • how big was the spider and what sex?;
  • how much venom was injected?;
  • what variability was there in the venom content on that day, from that spider?;
  • how large/old was the patient?;
  • what pre-existing diseases did the patient have, if any?;
  • what first aid was used?

While allergy to spider venom is possible, evidence currently available indicates it most likely plays a very small role, or no role at all, in spiderbite, in contrast to insect stings where it is a significant problem.

The factors mentioned above mean that there is a wide spectrum of severity for red back spider bites, from minimal effect to severe effects, and while patient factors can influence this, it seems likely that the most important factors, in most cases, are spider-related, except perhaps for the size of the patient. A small child is more likely to have more severe envenoming, simply because of the body mass versus venom mass equation; a smaller body mass means a higher dose of venom per kg, for a given amount of venom injected.

Are some people inherently more susceptible to the effects of red back spider venom?

There is no clear answer to this question, but theoretically it is possible that some people have subtle differences in receptor proteins on nerve cells that either enhance or reduce effectiveness of venom, but whether this plays a role in envenoming of humans by these spiders is speculative, not currently answerable with clear evidence.

What is clear to clinicians treating cases of significant red back spider envenoming is that in most cases specific antivenom appears to be the most effective treatment.” – Professor Julian White


So there we have it, the definitive answer. For some time I believed that maybe I was one of the lucky ones, my redback spider bite caused me very few problems, I thought maybe I was immune.

Then as more comments appeared on my original post I became unsure whether I really was a lucky one or not.

Now I do know for sure, I’m not one of the lucky ones; it’s much more likely that some other factor meant that I didn’t suffer as many others have.



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{ 2 comments… add one }
  • Jackie Clifton April 10, 2016, 10:49 pm | Link

    Quite enlightening. I was bitten 5 days ago, received no anti venom at the hospital, but am still in a lot of pain. Was it a redback? I still have the burning pain and ice makes it worse!

    • BobinOz April 11, 2016, 8:23 pm | Link

      Hmm, it’s difficult to say Jackie, if you visit my post called ‘What’s it really like to be bitten by a redback spider’, there is a link to it in the above article, you will read hundreds of comments from people who have also been bitten by these critters.

      It may help you identify whether it was a redback or not, some people have reported experiencing pain for quite some time. Have a read and feel free to ask for advice in the comments on that page as well if you wish. Cheers, Bob

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