The hand sanitizers you should avoid, including those made with low levels of alcohol or toxic levels of methanol

• The FDA recently warned against hand sanitizers with toxic levels of methanol, which can be deadly.
• Other hand-sanitizers, like varieties made from standard liquor or those that have expired, should be avoided too.
• It's always better to wash your hands with soap and water than to use even the most legitimate sanitizer.

Early in the pandemic, hand sanitizer flew off store shelves. But last week, the FDA warned that some varieties should stay there — or better yet, not be sold at all.

The nine hand-sanitizer products, produced by the company Eskbiochem SA de CV in Mexico, contain the toxic chemical methanol, which can be poisonous — leading symptoms like drowsiness, dizziness, headache, nausea, vomiting, and confusion — if it's ingested or absorbed through the skin.

But those aren't the only risky hand sanitizers. Experts say you should also avoid those with insufficient alcohol, expired products, and any sanitizer when soap and water are available.

The type and content of alcohol matter

First, as the FDA has called attention to, don't buy hand sanitizer made with methanol, a type of alcohol typically used in industrial settings and found in products like adhesives, paint thinners, and antifreeze, Insider's Julia Naftulin reported. Any product with more than 4% methonal must be labeled as "poison" in the US.

Safer varieties are made with either isopropyl (rubbing) or ethyl (used in beer, wine, and spirits) alcohol, but they need to contain at least 60% alcohol to be effective.

"The bottom line is that alcohol is the active ingredient," Miryam Wahrman, a biology professor at William Paterson University and the author of "The Hand Book: Surviving in a Germ-Filled World," previously told Insider.

If you make your own then by mixing isopropyl alcohol, which is often sold in 70% solutions, with aloe, for example, it's important to calculate correctly so you're no bringing the total alcohol content below 60%.

For the same reason, any hand-sanitizer made using standard alcohol from a liquor cabinet won't suffice: 70-proof vodka, for instance, is only 35% alcohol. Diluting it further to make it easier on your skin will render it near pointless.

The exceptions are the strongest liquors, like Everclear, which is sold in 151- and 190-proof varieties.

Distilleries manufacturing hand-sanitizers use ethyl alcohol, not the finished booze, to make their products, but you should still check the ingredient label to be sure.

Check the date and just wash your hands if you can

Store-bought sanitizers that are over three years past their manufacture date should generally be tossed, too, since with time the alcohol content declines. Usually, the product's expiration date will reflect that projection.

However, if you have no other choice, some alcohol is better then none, and if you haven't yet opened the container, it will be more effective than a three-year-old bottle that's half-empty, Alex Berezow, microbiologist and Vice President of Scientific Communications at the American Council on Science and Health, previously told Insider.

Finally, you should not use any hand-sanitizer — no matter how alcohol-packed and fresh it is — if the superior option, handwashing, is available.

Washing your hands with soap for at least 20 seconds removes germs from your skin and remains the best way to protect against the coronavirus and other pathogens. Hand sanitizer, by contrast, kills most germs but doesn't remove them from your skin, Wahrman said.

"Handwashing is the most important first step, and you shouldn't be bashful about it," she said.