How Does Qlaira Work in the Body
Chemical Composition, Mechanism of Action & Metabolic Effects Explained
Key Takeaways: How Qlaira Works
- Active ingredients: Estradiol valerate (oestrogen) and dienogest (progestin) in a four‑phase dynamic dose regimen.
- Primary actions: Prevents ovulation, thickens cervical mucus, alters endometrium to reduce heavy bleeding.
- Unique regimen: 26 active tablets (4 colour‑coded doses) + 2 placebo, designed to mimic natural cycle and minimise breakthrough bleeding.
- Metabolism: Estradiol valerate rapidly hydrolysed to natural 17β‑estradiol; dienogest metabolised via CYP3A4; both excreted in urine and faeces.
- Dual indication: Licensed for contraception and for treatment of heavy menstrual bleeding (not caused by organic pathology) in women choosing oral contraception.
Qlaira combines estradiol valerate and dienogest in a novel oestrogen‑based four‑phase pill. It provides reliable contraception while effectively reducing heavy menstrual bleeding through its dynamic hormonal delivery.
Important Medical Advice
Combined hormonal contraceptives like Qlaira increase the risk of venous thromboembolism (VTE). Seek urgent medical attention if you experience sudden leg swelling, chest pain, breathlessness, or severe headache. Do not use Qlaira if you have a history of blood clots, certain migraines, or liver disease. Always read the PIL.
Chemical Composition & Molecular Structure of Qlaira
Qlaira tablets contain two active substances: estradiol valerate (a prodrug of natural 17β‑estradiol) and dienogest (a unique progestin with anti‑androgenic properties). The four‑phase blister delivers varying daily doses:
- 2 dark yellow tablets: 3 mg estradiol valerate only
- 5 medium red tablets: 2 mg estradiol valerate + 2 mg dienogest
- 17 light yellow tablets: 2 mg estradiol valerate + 3 mg dienogest
- 2 dark red tablets: 1 mg estradiol valerate only
- 2 white tablets: placebo (inactive)
Structural Details
Estra‑1,3,5(10)‑triene‑3,17β‑diol 17‑pentanoate
An ester of natural oestradiol with valeric acid. The esterification increases oral absorption; after absorption it is rapidly cleaved to active 17β‑estradiol. Lipophilic (logP ~4.0) with high affinity for oestrogen receptors.
17‑hydroxy‑3‑oxo‑19‑nor‑17α‑pregna‑4,9‑diene‑21‑nitrile
A 19‑nortestosterone derivative with a cyanomethyl group. It combines progestogenic activity with partial anti‑androgenic effects and moderate anti‑gonadotropic activity. No androgenic, oestrogenic or mineralocorticoid activity.
Key Pharmaceutical Properties
| Property | Estradiol valerate | Dienogest |
|---|---|---|
| Lipophilicity (logP) | ~4.0 (as valerate) | 2.8 |
| Protein binding | 98% (to SHBG, albumin) | 90% (to albumin, not SHBG) |
| Oral bioavailability | 3‑5% (extensive first‑pass) | 96% |
| Receptor affinity | ERα / ERβ agonist | PR agonist (weak) |
| Volume of distribution | ~1.2 L/kg | ~40 L |
🗒️ Pharmaceutical insight: The four‑phase regimen provides oestrogen throughout the cycle, reducing oestrogen withdrawal symptoms and stabilising the endometrium – key for heavy menstrual bleeding control.
Mechanism of Action: Dual Qlaira Pathway
Qlaira exerts its contraceptive and therapeutic effects through complementary actions on the hypothalamic‑pituitary‑ovarian axis and peripheral target tissues.
- Ovulation inhibition: Dienogest suppresses the mid‑cycle LH surge, preventing follicular rupture. The oestrogen component helps maintain negative feedback on FSH.
- Cervical mucus thickening: Progestogenic action increases mucus viscosity, forming a physical barrier that impedes sperm penetration.
- Endometrial transformation: The phased oestrogen/progestin regimen induces secretory transformation and predictable shedding, reducing menstrual blood loss by up to 80% in clinical trials.
- Tubal motility alteration: Hormonal changes slow ovum transport, reducing the chance of fertilisation.
| Target | Estradiol valerate role | Dienogest role |
|---|---|---|
| Pituitary | Suppresses FSH (follicular development) | Blocks LH surge |
| Cervix | — | Thickens mucus |
| Endometrium | Proliferation control | Secretory transformation, atrophy |
| Fallopian tubes | Modulates peristalsis | Reduces motility |
🗒️ Physiological insight: The absence of a pill‑free interval (only 2 placebo tablets) minimises hormonal fluctuations, contributing to better cycle control and fewer heavy bleeding days.
Pharmacokinetics of Qlaira: Absorption & Distribution
After oral administration, both components are rapidly absorbed. Peak plasma concentrations are reached within 1‑2 hours for dienogest and 6‑8 hours for estradiol valerate (due to hydrolysis).
Absorption
Estradiol valerate is completely absorbed but undergoes extensive first‑pass metabolism in gut and liver (to estradiol, then estrone). Dienogest is almost completely bioavailable (96%) and not bound to SHBG, giving predictable free levels.
Distribution
Estradiol circulates bound to SHBG (60%) and albumin (38%). Dienogest binds only to albumin (90%), so its free fraction is unaffected by SHBG fluctuations. Steady state is reached after about 5 days.
Metabolic Effects & Elimination of Qlaira
Estradiol valerate: Rapidly hydrolysed by esterases to 17β‑estradiol, which is further metabolised in the liver to estrone, oestriol and conjugated metabolites (glucuronides/sulphates). CYP3A4 plays a minor role. Metabolites are excreted mainly in urine (60%) and faeces (35%).
Dienogest: Metabolised primarily via CYP3A4 to inactive hydroxylated derivatives, then conjugated. Unlike many progestins, it does not inhibit CYP enzymes. Excretion is renal (60%) and biliary (35%), with a terminal half‑life of 9‑10 hours.
⚠️ Metabolic caution: Strong CYP3A4 inducers (rifampicin, carbamazepine) may accelerate metabolism and reduce contraceptive efficacy. Qlaira does not affect liver function tests significantly, but regular monitoring is advised in hepatic impairment.
Clinical Efficacy of Qlaira: Contraception & Heavy Menstrual Bleeding
Qlaira is the only combined pill approved for both contraception and treatment of heavy menstrual bleeding (HMB) in women choosing oral contraception. In pivotal trials:
- Pearl Index (contraceptive failure) 0.40 (typical use).
- Menstrual blood loss reduced by 70‑80% after 6 months, sustained for up to 1 year.
- Bleeding patterns: Scheduled withdrawal bleeding usually starts during the second dark red tablet or placebo phase; unscheduled spotting decreases over time.
The dynamic dosing mimics the natural cycle’s oestrogen rise and fall, providing excellent cycle control and high user satisfaction.
Qlaira FAQs
How quickly does Qlaira start working for contraception?
If started on the first day of your period, protection is immediate. If started later, use additional barrier methods for the first 7 days.
Can Qlaira help with heavy periods?
Yes, Qlaira is specifically licensed to treat heavy menstrual bleeding (menorrhagia) in women who also need contraception. It reduces blood loss by stabilising the endometrium.
What should I do if I miss a Qlaira tablet?
If you are less than 12 hours late, take it immediately. If more than 12 hours, follow the PIL chart: the risk depends on which day you missed. Use extra precautions for 7 days.
Does Qlaira cause weight gain?
Common side effects include weight gain in about 1‑10% of users, but it varies individually. Dienogest has a neutral metabolic profile compared to older progestins.
Can I take Qlaira while breastfeeding?
Generally not recommended as oestrogens may reduce milk supply. Discuss progestin‑only options with your doctor if you are breastfeeding.
Need Qlaira Prescribed Online?
If you are considering Qlaira for contraception or heavy periods, a UK‑registered doctor can assess your suitability through a discreet online consultation.
Secure Prescription & Next‑Day Delivery
MHRA‑compliant | GPhC‑registered pharmacy | Discreet packaging | UK‑registered doctors
Start Contraception ConsultationRelated Qlaira Guides
Medical Content Manager
Nabeel is a co-founder, and medical content manager of Chemist Doctor. He works closely with our medical team to ensure the information is accurate and up-to-date.
Medical Doctor
Dr. Feroz is a GMC-registered doctor and a medical reviewer at Chemist Doctor. He oversees acute condition and urgent care guidance.
Medical Director
Usman is a co-founder, and medical director of Chemist Doctor. He leads the organisation's strategic vision, bridging clinical and operational priorities.
Review Date: 17 March 2026
Next Review: 17 September 2026
Published on: 17 March 2026
Last Updated: 17 March 2026