Orilissa (elagolix) is a prescription pill used to treat pain caused by endometriosis. It targets two specific types of endometriosis pain: painful periods (dysmenorrhea) and pelvic pain that occurs outside of menstruation. It was the first oral medication specifically designed to manage endometriosis pain by lowering estrogen levels without requiring injections or implants.
How Orilissa Works
Endometriosis pain is driven largely by estrogen, which stimulates the growth of tissue similar to the uterine lining in places where it doesn’t belong. That tissue triggers inflammation both locally and throughout the body, causing chronic pain. Orilissa works by blocking a specific hormone receptor in the brain that controls estrogen production. By occupying that receptor, the drug rapidly reduces the signals that tell the ovaries to produce estrogen, and estrogen levels drop within days of starting treatment.
Older injectable medications that target the same hormonal pathway cause an initial spike in symptoms before eventually suppressing estrogen, sometimes called a “flare effect.” Orilissa skips that phase entirely. Because it competitively blocks the receptor rather than overstimulating it, estrogen suppression begins right away.
Two Doses for Different Situations
Orilissa comes in two dosing options, and the choice depends on the type of pain being treated. The lower dose, 150 mg taken once daily, is the standard starting point for most people and can be used for up to 24 months. It’s designed for general endometriosis-related pelvic pain and painful periods.
The higher dose, 200 mg taken twice daily, is reserved for people who also experience dyspareunia (pain during sex). Because this dose suppresses estrogen more aggressively, it comes with a shorter treatment window of six months maximum. Treatment is typically started within seven days of the beginning of a menstrual period.
Orilissa Is Not the Same as Oriahnn
The active ingredient in Orilissa, elagolix, also appears in a separate medication called Oriahnn, which treats heavy menstrual bleeding from uterine fibroids. The two are not interchangeable. Oriahnn combines elagolix with estradiol and a progestin to offset the bone and hormonal effects of estrogen suppression. Orilissa, on the other hand, contains elagolix alone and is approved only for endometriosis pain. If you’ve heard elagolix mentioned in the context of fibroids, that’s the Oriahnn formulation.
Common Side Effects
Because Orilissa lowers estrogen, many of its side effects resemble what happens during menopause. Hot flashes are the most common, affecting about 24% of people on the lower dose and 46% on the higher dose (compared to 9% on placebo). Other frequently reported side effects from clinical trials include:
- Headache: 17% at the lower dose, 20% at the higher dose
- Nausea: 11% to 16%, depending on dose
- Insomnia: 6% to 9%
- Mood changes or mood swings: about 5% to 6%
- Depression or depressive symptoms: 3% at the lower dose, 6% at the higher dose
- Joint pain: 3% to 5%
- Missed periods: 4% to 7%
In clinical trials, about 5.5% of people on the lower dose and 9.6% on the higher dose stopped taking Orilissa because of side effects. The most common reasons for stopping were hot flashes, night sweats, and nausea. Side effects were consistently more frequent with the higher dose, which is one reason its use is capped at six months.
Bone Density Loss
Estrogen plays a key role in maintaining bone strength, so suppressing it raises concerns about bone thinning. Orilissa does cause some bone mineral density loss, and this is the primary reason treatment duration is limited. The effect is dose-dependent: the higher dose causes more bone loss, which is why it’s restricted to six months compared to 24 months for the lower dose.
Research into pairing elagolix with “add-back therapy,” a small amount of hormones given alongside the drug to protect bones, has shown promising results. In a phase 3 trial, bone mineral density loss with add-back therapy was less than 1%, significantly less than with elagolix alone. People who already have osteoporosis should not take Orilissa.
Who Should Not Take Orilissa
Orilissa is not safe for everyone. You should not take it if you are pregnant, have osteoporosis, or have severe liver disease. People with moderate liver impairment can use only the lower 150 mg dose, and only for up to six months. The higher dose is not recommended for this group at all.
Certain medications that affect how the liver processes drugs can cause elagolix to build up to unsafe levels in the blood. These are a class of drugs known as OATP1B1 inhibitors. If you’re taking other medications, your prescriber will need to check for interactions before starting Orilissa. A history of serious allergic reaction to any ingredient in Orilissa also rules it out.
What to Expect on Treatment
Orilissa is a daily pill, which distinguishes it from older hormone-suppressing treatments that required monthly injections or surgical implants. Clinical trials showed meaningful reductions in both menstrual pain and non-menstrual pelvic pain compared to placebo. Because the drug begins blocking estrogen production quickly, without the flare period associated with older treatments, symptom relief can begin relatively early in the course of treatment.
Orilissa is not a cure for endometriosis. It manages pain by keeping estrogen levels low, and symptoms can return after stopping the medication. It also does not act as a contraceptive, so pregnancy prevention should be addressed separately. Because of the time limits on use (six months for the higher dose, two years for the lower dose), it’s often part of a broader treatment plan that may include other pain management strategies or surgery.