On The Efficacy of Avon Skin So Soft As A Mosquito Repellent

 

It's no exaggeration to say that, when question arise as to recommendations for mosquito repellents, Avon Skin So Soft is one of the most discussed products.  So, a simple question: does it work.  Or to be more precise, how well does it work when compared with proven repellents like DEET.

So, let’s be clear about the standards we’re discussing.  The scientific way to test repellents is to apply some to a subject’s arm, and place it in a mosquito cage.  Once the arm is left in for a set amount of time, it’s taken out, then returned after a set amount of time, usually waiting for an hour in the first instance.  This continues until the repellent has been deemed to have ‘failed’.  In these tests, a ‘fail’ is if the subject is bitten twice on any one insertion to the cage, or once on two consecutive insertions.

For anyone who doesn’t know what it looks like, or how effective DEET (the industry gold standard) is, here’s a video.

 

Before we go any further, there’s something which needs to be made clear.  This video isn’t cherry-picked.  This test isn’t cherry-picked.  This is what has happened every time DEET has been tested.  And that’s a lot of times, literally thousands of subjects over the last 70 years.  There’s never been an instance where half-a-dozen subjects have been called in to be tested, and five are bite-free, but the 6^th gets bitten all over.  It’s never happened.  That’s how well DEET works for everyone (but see below*).

There is an alternative test, which is to apply the repellent and send the subjects out into an area where mosquito bites are common.   The advantage is that this is more ‘real world’.  The disadvantages are that you have no control over the density of mosquitos at the time of testing (something likely to fluctuate between tests) and it’s very difficult to test efficacy over time.  In a lab you can sit next to a mosquito cage, and re-insert your arm every hour, then look to see if there are any bites.  In the jungle you have to return to base, check for bites, then return to the wild.  As a result, most in-the-field tests are only conducted for a set, relatively short period of time, usually 1-2 hours.

Okay, we need to link to two scientific papers comparing DEET to Avon Skin So Soft.  One is a mosquito cage test, and one is ‘in the field’.

Here’s the first, it's an in-the-field test (I’ll provide a precis):

https://pubmed.ncbi.nlm.nih.gov/2045813/

Precis: A number of tests were conducted, each lasting 90-120 minutes.  Subjects were sprayed with DEET, Avon Skin So Soft, a special formula, and a placebo, rotating between the right arm, left arm, right leg, and left leg, so each had a fair share of the four repellents. They were then sent into the jungle.

At the end of the test 74 ‘events’ (bites causing a pruritic papule) occurred.  Placebo site 40 bites, special formula 28 bites, Avon Skin So Soft 6 bites, DEET 0 bites.

So it’s a ‘win’ for DEET, but you might be forgiven for giving a mild pat on the back to Avon Skin So Soft.  Effectively 6 bites instead of 40 for the placebo, that’s certainly better than nothing.

However, one perhaps needs to imagine a customer entering a shop and asking if they stocked any mosquito repellents.  The staff member says they have two.  If you don’t wear a repellent you might be bitten 40 times, if you wear one of the two they stock you’ll be bitten on average 6 times, but if you wear the second, you shouldn’t be bitten at all.  What would we think of the customer who smiles and asks politely for the one where they’ll be bitten 6 times, instead of the one where they won't get bitten at all.

Okay, there is another test.  It doesn’t contradict the previous one, but adds to it:

https://www.nejm.org/doi/full/10.1056/NEJMoa011699

Again, a precis.  The DEET (23.8%) lasted a mean average of just over 5 hours.  This is in line with other tests, where 50% DEET has been found to last c.8 hours (in some tests up to 12 hours).  Avon Skin So Soft (and all the other non-DEET-based repellents) all failed after 90 minutes.  For clarity, that's the mean average time for a fail, so some subjects were bitten on their initial insertion (immediately after application) and some at the first 1 hour test.

So, does Avon Skin So Soft ‘work’?  The most positive spin one could put on it is to say it may work for a short while, but with no guaretees, and requires multiple reapplications.  You're likely to get fewer bites than if wearing no repellent, but you'll still get some.  Re-applying regularly may be possible at the beach, where people are used to re-applying sun lotion regularly, and need to reapply any repellent after going for a swim.  But for a night out it’s problematic, and would involve applying and reapplying perhaps five times, including mid-meal.  And re-applying every 60 minutes on the beach, without fail, over a 14 day holiday is going to make Avon Skin So Soft an extremely expensive option.

But as ever, you pays your money, and you makes your choice.

* A word on the real-world efficacy of DEET.  Every now and then someone wears DEET, but is still bitten.  There are a number of explanations as to why this will inevitably happen from time-to-time.  These would include not applying it correctly **, missing a bit, the DEET getting washed or rubbed off, forgetting to apply it (and maybe forgetting that you forgot), or not re-applying frequently enough, or maybe that bite isn’t a mosquito bite.

** You need to rub it in over every exposed surface: I’ve had people say they spray it in the air and walk through it like applying perfume, and even (and I‘m being serious here) dabbing a bit of DEET on their ankles and wrists.