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Side Effects


Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

ella was studied in an open-label multicenter trial (Open-Label Study) and in a comparative, randomized, single-blind, multicenter trial (Single-Blind Comparative Study). In these studies, a total of 2,637 (1,533 + 1,104) women in the 30 mg ulipristal acetate groups were included in the safety analysis. The mean age of women who received ulipristal acetate was 24.5 years and the mean body mass index (BMI) was 25.3. The racial demographics of those enrolled were 67% Caucasian, 20% Black or African American, 2% Asian, and 12% other.

The most common adverse reactions ( ≥ 10%) in the clinical trials for women receiving ella were headache (18% overall) and nausea (12% overall) and abdominal and upper abdominal pain (12% overall). Table 1 lists those adverse reactions that were reported in ≥ 5% of subjects in the clinical studies (14).

Table 1: Adverse Reactions in ≥ 5% of Women (%) Receiving a Single Dose of ella (30 mg Ulipristal Acetate)

Most Common Adverse Reactions Open-Label Study
N = 1,533
Single-Blind Comparative Study
N = 1,104
Headache 18 19
Nausea 12 13
Abdominal and upper abdominal pain 15 8
Dysmenorrhea 7 13
Fatigue 6 6
Dizziness 5 5

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of ella: Skin and Subcutaneous Tissue Disorders: Acne

Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Read the Ella (ulipristal acetate tablet) Side Effects Center for a complete guide to possible side effects


Several in vivo drug interaction studies have shown that ella is predominantly metabolized by CYP3A4.

Changes In Emergency Contraceptive Effectiveness Associated With Co-Administration Of Other Products

Drugs or herbal products that induce CYP3A4 decrease the plasma concentrations of ella, and may decrease its effectiveness [see WARNINGS AND PRECAUTIONS and Pharmacokinetics]. Avoid co-administration of ella and drugs or herbal products such as:

  • barbiturates
  • bosentan
  • carbamazepine
  • felbamate
  • griseofulvin
  • oxcarbazepine
  • phenytoin
  • rifampin
  • St. John's Wort
  • topiramate

Increase In Plasma Concentrations Of ella Associated With Co-Administered Drugs

CYP3A4 inhibitors such as itraconazole or ketoconazole increase plasma concentrations of ella [see Pharmacokinetics].

Effects Of ella On Co-Administered Drugs

In vitro studies demonstrated that ella does not induce or inhibit the activity of cytochrome P450 enzymes.

P-glycoprotein (P-gp) transporters: In vitro data indicate that ulipristal may be an inhibitor of P-gp at clinically relevant concentrations. Thus, co-administration of ulipristal acetate and P-gp substrates (e.g., dabigatran etexilate, digoxin) may increase the concentration of P-gp substrates. In vivo data suggest that ulipristal acetate 10 mg does not affect P-gp transporters. However, there was no in vivo drug interaction study between ulipristal acetate 30 mg and P-gp transporters [see Pharmacokinetics].

Read the Ella Drug Interactions Center for a complete guide to possible interactions

Last reviewed on RxList: 6/30/2014
This monograph has been modified to include the generic and brand name in many instances.

Side Effects

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You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Women's Health

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