Plastic bottle of mouthwash left for 3 weeks in high temperatures: safe?
July 12, 2013 4:17 PM   Subscribe

I accidentally left an unopened plastic bottle of mouthwash in my car for 3 weeks in high temperatures. Is it still safe to use?

The past 3 weeks have been very hot here, with temperatures in the high 80s and 90s and my car interior is black. I'm concerned about the effect of the heat on the plastic, whether that would have made chemicals leach into the contents of the bottle. Then again, you do spit mouthwash out...

On the bottom of the bottle, it has the numeral 1 inside the recycling symbol. It's a huge bottle and is unopened so I would rather not throw it out...
posted by galenka to Health & Fitness (10 answers total)
The bottle is made of food grade plastic. It is fine to use. Nothing harmful will "leach".

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posted by Tanizaki at 4:33 PM on July 12, 2013 [1 favorite]

Hmmm. Do you swig from it?

In my unscientific mind, I'd be hesitant to take in old mouth germs that've been sitting in a heated Petri dish for 3 weeks.
posted by vitabellosi at 4:59 PM on July 12, 2013

heated Petri dish for 3 weeks.

It's mouthwash, it's entire purpose it to kill germs.

And the plastic is no less safe now than it was three weeks ago. The mouthwash has always been in plastic, probably for months, getting up to 120 degrees or so isn't going to make a difference, unless the bottle is actually melted, in which case, there's probably no more mouthwash in it anyway.
posted by tylerkaraszewski at 5:11 PM on July 12, 2013 [3 favorites]

A petri dish has nutrients designed to encourage the micro-organisms to thrive. Mouthwash has poisons to kill the critters. Go ahead, it's fine.

Also, there's no bacteria in there if it's an unopened bottle of mouthwash. You're safe.
posted by pines at 5:14 PM on July 12, 2013 [4 favorites]

It also probably gets pretty hot inside the warehouse and the semi truck on the way from factory to store.
posted by sanderman at 5:39 PM on July 12, 2013 [2 favorites]

I think people are missing the fact that this is an unopened bottle. No mouth germs have gotten a chance to get in.

This type of stuff is shipped in un-refrigerated trucks, and often stores in poorly if at all climate controlled warehouses(have you read the stories about pickers in warehouses lately? it gets close to 100 in there often).

The materials the package and the formulation of the mouthwash itself were designed to withstand this sort of abuse, it'll be fine.
posted by emptythought at 6:03 PM on July 12, 2013 [1 favorite]

I used to keep a bottle of mouthwash in my car door that I would occasionally swig from. I had it in there for probably nine months, including a very hot summer. It never occurred to me to be concerned about it until I saw this question. Nonetheless, I think you are OK.
posted by ista at 6:55 PM on July 12, 2013

I think people are missing the fact that this is an unopened bottle. No mouth germs have gotten a chance to get in.

You guys are completely right. No matter how many times I read the question, I kept thinking "how do you leave a bottle, opened, in the car for three weeks?"

Swish away!

(Also, I know mouthwash's job is to kill germs, but still...old mouth germs + 90 degree weather. If that had been the case...)
posted by vitabellosi at 7:47 PM on July 12, 2013

What is the expiration date printed on the bottle?

Keeping the bottle in a hot car is like performing accelerated stability; reactions, including the breakdown of the active ingredients, proceed more quickly at elevated temperatures. This method is a simplification but we don't know what the critical reactions are for your bottle of mouthwash so.

Assuming you have a commercial major/store brand bottle held for three weeks around/above 105 F (as it would get inside your car) I would move the expiration date up by 6 months. I, personally, would discard the bottle on or near that moved up expiration date. I would treat this differently than shampoo or salad dressing because the mouthwash (presumably) has active ingredients.

If this is a prescription bottle the expiration date is likely to be closer to manufacture and I would probably discard the bottle now.
posted by mountmccabe at 6:16 AM on July 13, 2013

FWIW -- I just spent a few weeks at a summer cottage that hasn't really been "lived in" for about a decade. Everything in the bathroom was expired. Some items expired in the 80's. The house has no insulation and gets blazing hot in the summer and literally freezes in the winter.

The point is, I used mouthwash I found there that expired sometime around the year 1999. It was listerine, the green kind. I am still alive, and have suffered no ill effects.

You should use your bottle of mouthwash. It is absolutely 100% fine.
posted by RingerChopChop at 6:18 PM on July 13, 2013

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