“As you guys know my#morningsickness has been pretty bad,” the celebrity wrote in part in an Instagram post Sunday. “I tried changing things about my lifestyle, like my diet, but nothing helped, so I talked to my doctor. He prescribed me #Diclegis, I felt a lot better and most importantly, it’s been studied and there was no increased risk to the baby.”

OMG. Have you heard about this? As you guys know my #morningsickness has been pretty bad. I tried changing things about my lifestyle, like my diet, but nothing helped, so I talked to my doctor. He prescribed me #Diclegis, I felt a lot better and most importantly, it’s been studied and there was no increased risk to the baby. I’m so excited and happy with my results that I’m partnering with Duchesnay USA to raise awareness about treating morning sickness. If you have morning sickness, be safe and sure to ask your doctor about the pill with the pregnant woman on it and find out more www.diclegis.com; www.DiclegisImportantSafetyInfo.com

A photo posted by Kim Kardashian West (@kimkardashian) on Jul 19, 2015 at 6:04pm PDT

The company followed up with a press statement the next day, writing that they were proud that the drug was helping the reality star mom combat morning sickness — a pregnancy symptom about which Kardashian West has been open on Twitter and in interviews.

The move has drawn sharp criticism from fans who decried her willingness to make a quick buck. Despite the medication’s bonafides (it’s FDA approved, which stands in stark contrast to the dubious, dangerous diet pills Kardashian West has shilled in the past), her Instagram post highlights a controversial American quirk in pharmaceutical regulation. While most countries ban any direct-to-consumer drug advertisements, much less celebrity endorsements of such products, it’s a prominent part of U.S. culture. Think of Paula Deen, who promoted a diabetes drug after she made a career celebrating an unhealthy dietary lifestyle, or former presidential candidate Bob Dole, who became a spokesman for Viagra in 1996.

Morning sickness during pregnancy is mis-named; the nausea and vomiting can strike at any time of day, and while it’s most common during the first trimester of pregnancy, some women feel its effects for longer. Kardashian West, who is currently five months pregnant, appears to be one of those women.

While it’s an almost universal experience for pregnant women, scientists still aren’t completely sure what causes morning sickness, although the rapid rise of the so-called “pregnancy hormone” human chorionic gonadotropin, which helps with egg implantation and placenta growth and peaks near the end of the first trimester, is the prime suspect. Some researchers have also hypothesized that the condition serves an evolutionary purpose by making the mother more wary of potentially harmful foods during the most delicate stage of the pregnancy.

Usually, doctors recommend solutions like eating small, frequent meals, bland, carbohydrate-rich foods, and ginger ale to avoid the worst morning sickness symptoms. Diclegis, a prescription-only drug, is the only FDA-approved medicine for morning sickness and bills itself as medicine for “women who do not respond to conservative management.”

However, it has not been tested in women with the worst kind of morning sickness: hyperemesis gravidarum, a rare condition in which a pregnant mother vomits so much that she is at risk of dehydration and significant weight loss. Catherine, Duchess of Cambridge, is probably the most high-profile example of this condition. Buckingham Palace famously had to announce both of her pregnancies before the end of her first trimesters because she was treated for hyperemesis gravidarum.

Like all drugs, Diclegis has serious side effects. Women who are breastfeeding, have asthma, certain eye problems or stomach and bladder issues should avoid it, and it can cause serious drowsiness. Diclegis also interacts with the ingredients of a type of antidepressant called a monoamine oxidase inhibitor, or MAOI, and should not be taken by women who rely on these drugs.

Critics of direct-to-consumer drug advertisements say that the commercials interfere in the relationship between doctor and patient, and breed distrust in treatment recommendations that are not prominently advertised. They could also over-emphasize a drug’s benefits, which leads to over-prescription or misuse of the medicine.

And while the pitfalls of celebrity health endorsements are obvious (like Jenny McCarthy’s harmful anti-vaccination stance, or Gwyneth Paltrow’s unhealthy detox cleanses), there’s some evidence that they may not even work the way pharmaceutical companies intend. Nilesh Bhutada, a professor and researcher at California Northstate University College of Pharmacy who specializes in studying direct-to-consumer pharmaceutical advertising, says that there’s no proof that celebrities have any impact at all on someone’s medication choices.

“When you use celebrities in your advertisements, they do attract a consumer’s attention,” he admitted to HuffPost. “But at least in our research, we have not found that celebrities have any impact on whether or not consumers demand the product at their next doctor’s visit.”

Luckily, in this case, whatever you think of the wisdom behind Kardashian West’s decision to endorse the morning sickness pill, Diclegis is FDA approved and available only with a doctor’s prescription.