The Kardashian-Jenners' Go-To Doctor Reveals the Cosmetic Procedures Tons of Stars Are Doing

From high-tech facials to skin-tightening lasers, celebrities are all about testing out the latest treatments — and Beverly Hills doctor Dr. Simon Ourian, who practices cosmetic dermatology, is one of Hollywood’s most in-demand specialists. With most of his clientele ranging from A-list actors to musicians and models, Ourian has given countless celebs an ageless appearance that looks so natural, you probably can’t even tell they’ve had any work done at all.

Ourian helps stars like Kim Kardashian West, Khloé Kardashian, Kylie Jenner, Christie Brinkley, Olivia Culpo, Jenna Dewan and countless others take care of their complexions, thanks to quick non-invasive treatments that require minimal downtime. And now, he’s revealing his secrets.

“These procedures are more predictable than surgery and they are reversible in most cases, requiring minimal to no downtime,” Ourian tells PEOPLE. “The results can be adjusted and navigated with each treatment, and if done correctly, there are no telltale signs, which is why celebrities are more interested in this than ever before.”

Even though downtime for most of these celeb-loved treatments is minimal, Ourian does note that there are some side effects that he warns patients about ahead of time before getting any cosmetic injection.

“There can be swelling, temporary discoloration, unevenness and bruising — however, the more experience and reputation the doctor has, the less of a chance that these will happen or last long,” he says. “To help with it, icing is very effective, as well as staying out of the sun and having some down within the day or so after your treatment.”

While Ourian can’t disclose exactly which cosmetic procedures he does on specific stars, he shared the top five most-requested treatments in Hollywood with PEOPLE below.

Non-Surgical Jawline Contouring

The Procedure: “We add fillers to strategic points on the face to create more of a straight line and angle from the chin to right below the ear. I measure all the angles beforehand to make sure that it is done matching the person’s face,” Ourian explains.

“I place the filler perpendicularly exactly on top of the jaw to make it as straight as possible. I get people all over the age spectrum who want to do this. People in their 20s want a more chiseled jawline or contoured look, but this can reverse aging in older clients as well. I recommend a temporary filler that lasts two to three months for a trial period and then building up to a product that lasts longer. The majority of my patients use fillers that last anywhere from two to five years for jawline contouring.”

The Price Tag: Between $500 to $2,000 (for short-term fillers like Restylane, Refyne or Vollure, which last three to six months) or $5,000 to $10,000 (for long-term fillers like Calcium hydroxylapatite or Poly-L-lactic Acid (PLLA), which last one to three years)

Non-Surgical Cheek Augmentation

The Procedure: “If you look at most models, they have a very beautiful high cheekbone. There are some people who have an apple cheek (when the front is bigger) and there’s some people who have more bone structure that goes all the way back. I like to create the second one by adding micro-droplet filler injections at many different layers of the cheek,” Ourian says.

“By doing this, it makes the cheekbone appear higher and more elongated. I use different products customized to each person for the most natural results. For a lot of my celebrities who are photographed 500 times a day, they need to have a face that nobody can detect what has been done the day before. The bruising for this is very minimal, so most patients go back to work the same day.”

The Price Tag: Between $1,000 to $3,000 (for short-term fillers) or $5,000 to $10,000 (for long-term fillers)

Non-Surgical Fox Eyes

The Procedure: “This gives the ‘cat eye effect’ or the look when you wear a tight ponytail that pulls back the eyes for a nice lift. A lot of people request their eyes be done that way, and want to try a non-surgical option first,” Ourian says.

“To achieve this, I use two different methods. First, I use a laser, like Coolaser, to shrink and tighten the skin directly above the eyebrows. That can last anywhere from two to five years, so clients don’t need touch-ups as frequently. Then, I also may add volume underneath the eyes using fillers to create more support and lift them up. In some cases, I may put fillers near the hairline for more of a lift too.”

The Price Tag: Between $3,000 to $15,000 depending on the combination of lasers and fillers used

Non-Surgical Lip Augmentation

The Procedure: “Lip fillers really became very popular a couple years ago when Kylie Jenner announced that I had done her lips,” Ourian explains. “Many people come here and asked me to do their lips exactly the way I did Kylie’s. Whether yours are thin or more plump naturally, if you respect the anatomy of the face they can always look a little bit better.”

“My biggest pet peeve is when people make their lips too big and they’re protruding out of their face. They really should just enhance your face, so I like to inject gradually and have clients come back in a month or two to see if they would like more. I always warn everyone to not judge yourself for the first 24 to 48 hours after the injection because you’re going to look really swollen. It’s unusual to look at, but the final results can be seen after about a week.”

The Price Tag: Between $1,000 to $2,000 (for short-term fillers) or $4,000 to $5,000 (for long-term fillers)

Non-Surgical Butt Augmentation

The Procedure: “I get a lot of younger celebrities asking for this because they will be wearing a bikini or tight, tight shorts and want to show off the behind all day. To make the butt look bigger, you can either do a fat transfer (which is known as a Brazilian butt lift) or inject fillers. But since a lot of the people who come to my practice don’t have enough fat, I use fillers most often,” he says.

“Right now in the U.S., we have two different types of fillers that can be used for a butt augmentation, but since you need to use so much, it can be very costly. I normally tell people don’t expect to go three sizes bigger. We can achieve a firmer, more lifted buttocks and correct any indentations.”

Before getting a cosmetic procedure done yourself, Ourian advises you do your research and find the right, reputable doctor for you.

“People can have serious health issues if they get injected with illegal fillers in the buttocks. Do not do it! It is so dangerous,” he says. “Use a reputable doctor who is reliable and trusted.”

The Price Tag: Between $20,000 to $40,000 (for a fat transfer augmentation) or $30,000 to $40,000 (for an augmentation using fillers)