Blame the ’80s (or Elle Woods’ brilliant legal defense against Chutney Windham), but perms have earned a bad rap. The mere mention of the word immediately conjures images of fried, frazzled strands, which is enough to make anyone think twice before putting their hair through the process. But in reality, do perms ruin your hair, or have we all been living a pop-culture-perpetuated lie?

The answer, according to pros, is “it depends.” More specifically, it depends on your hair texture and what you’ve done to it in the past. Read on for everything you need to know before trying out the treatment for yourself.

First up: What the heck’s a perm?

Simply put, a perm is a chemical curling treatment for your hair—not to be confused with a relaxing treatment, which effectively does the opposite and uses chemicals to straighten hair (and, confusingly, is sometimes referred to as a “straight perm”). The curl-perm process adds body and volume to flat or straight hair, giving it more volume and making it easier to style.

“A perm reprograms the hair internally by breaking down its natural molecular structure,” says New York City-based hairstylist Priscilla Flete. “Generally, the perming solution will soften and swell the hair by opening the cuticle and allowing the solution to penetrate the cortex [the innermost part of the hair strand].”

When you go into the salon, your stylist will wrap your hair around perming rods (which will determine the size and style of your curls), and then coat hair with perm lotion. Depending on your stylist’s technique and the size of the rods they’re using, you can get everything from beach waves to tight ringlets. “The perm lotion deposits hydrogen, which attaches itself to the hair structure’s disulfide bonds,” says Trey Gillen, hairstylist and artistic director at Sachajuan. “These bonds are then broken and become disulfide bonds, bringing the hair into a state that’s able to change to the new shape of the perming rods.” Then comes neutralizing, in which another solution is applied to halt the process and set the style into curls.

Who should get a perm, and who should not get a perm?

Generally speaking, healthy hair is the best suited for perming. “Perms generally work on all hair types, but the ideal candidate for a perm would be someone who has virgin hair or someone who has never colored their hair before,” says Flete.

However, it’s important to remember that perms are fairly intensive chemical treatments, so if you’re wondering “Can I perm damaged hair?” experts say it’s probably not the best idea. “Damaged or dry hair would need to build up its condition before the treatment to see if perming is a good option,” says Morganson, adding that she doesn’t perm lightened hair because the risk of damage is much higher on bleached strands. And if you have fine hair or hair that’s already compromised from any sort of colorant, your strands may be to fragile to hold up in the process.

Do perms ruin your hair?

The perming process has (thankfully) come a long way since the ’80s. New formulas have allowed modern perms to be less damaging than their old-school predecessors, but there are still a few things worth being aware of for the health of your hair. While perms don’t strip your hair the way bleach does, they do still change the chemical composition of your hair cuticle, which means you need to be careful if you decide to get one.

Virgin, unprocessed hair will usually be A-OK to go through the perming process. But a general rule to keep in mind? The more chemicals you’re putting in your hair, the more damage they’re likely to do. “Perms get a bad rap because, ultimately, it is a chemical process that permanently changes the hair, which can affect the hair if done incorrectly or if the hair was already chemically processed,” says Flete. Gillen adds that you can change the color or the texture of your hair individually, but you shouldn’t try to change both at the same time.

And one more thing—if you don’t want to damage your hair, don’t try this at home. Perms should always be performed by a professional who knows what they’re doing—and who will be able to tell you if your hair won’t be able to hold up to the treatment. “If done correctly by a professional on hair that is healthy and not overly processed, though, there shouldn’t be any damage,” says Flete.

What damage does a perm do to your hair?

According to Kim Mogensen, a Redken Artist at Timothy Roberts Hair Studio, “worst case breakage” can occur after a perm. A few tell-tale signs to look out for:

• Roughness around the hair cuticle
• Dryness
• Dullness
• Brittleness
• Breakage
• Frizz
• Weakness/lacking protein
• Difficulty combing your fingers through wet strands

Are some perms safer than others?

There are a lot of different types of perm treatments out there (loose, spiral, wavy), but they’re all generally equal as far as the damage they cause goes.  “The process of perming, regardless of the wrapping method, is all the same on the hair strand,” says Morgenson. 

But though the technique a stylist uses doesn’t make any different, the chemicals they use certainly do. “Alkaline perms are the most damaging to your hair because our hair lives on the acid side of the pH scale,” says Gillen. “Most perm solutions, like ammonium thioglycolate, are very high on the alkaline side, around 9.5.” There is such a thing as an acid perm, but while these are less damaging to strands, they can cause allergic reactions on your scalp.

Ultimately, the safety of any type of perm “comes down to proper consultation,” says Morgenson. “Having an experienced professional makes all the difference, because every head of hair is different. A professional who is well versed in perming will make the proper wrap choice and type of perm decision that fits the guest.”

How often can you perm your hair?

Aside from the fact that perming colored hair probably isn’t a good idea, it’s also worth noting that the more frequently you perm your hair, the more damage you’re likely to cause. “The real damage happens when you apply your next perm after perm after perm, which causes breakage,” says Gillen. With that in mind, you should wait at least six to eight weeks between perm treatments, and always consult with your stylist to determine whether or not your hair is ready for another round of chemicals.

How to care for your hair post-perm

Although the word “perm” may have you thinking “permanent,” the curls or waves the process creates generally only stick around for three to six months. “Once the service is completed, try to avoid wetting or washing your hair—it’s important to let the solution set in your hair for at least 48 hours,” says Flete. “Limit straightening your hair afterward as well, as this will cause the hair to straighten over time. And use products that are tailored to your new texture.”

But while the style itself isn’t permanent, the chemical process done to your hair is. “When we talk about having ‘virgin hair,’ you would have to grow out and cut the processed hair if you want to completely get rid of any chemical process in your hair,” says Flete. Aside from staying far, far away from color treatments before and after your perm, there are a few other things you can do to keep hair looking and feeling its best. “To maintain the style and to keep permed hair healthy, avoid using heat, use products to help support your new texture, and sleep with a satin pillowcase,” says Flete. Gillen recommends using Sachajuan Overnight Hair Repair ($53) a few nights a week, which will help provide moisture to your strands and repair any damage.

Final takeaway

Perms, like most chemical hair treatments (keratins, color, relaxers), have their pros and cons. If you’re looking for more volume and body to naturally straight, virgin hair, then a perm could be a great temporary treatment to explore. Of course, you want to ensure you’re doing your research by visiting a hairstylist who is well-versed in perms. You also want to consider upkeep: a perm will require avoiding heat and color services (so you want to avoid booking a perm followed by a full set of highlights). You should also keep the right products in your toolkit (satin pillowcases, hair masks, etc.) to make sure your new style stays looking and feeling as healthy as possible.