Allylestrenol – Uses, Dosage, Side Effects, Interactions

Last updated: February 8, 2026Reviewed date: February 8, 2026Reading time: 11 min read
Allylestrenol - Uses, Dosage, Side Effects, Interactions
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Article Summary

Allylestrenol is a steroid. It derives from a hydride of an estrane. A synthetic steroid with progestational activity. It is widely marketed throughout Europe, including Russia and many other European countries, and is also available in Japan, Hong Kong, India, Bangladesh, Indonesia, and much of Southeast Asia, though notably not in the United States or Canada. A synthetic steroid with progestational activity. Allylestrenol is a progestogen structurally related...

Key Takeaways

  • This article explains Mechanism of Action  in simple medical language.
  • This article explains Indications in simple medical language.
  • This article explains Contraindications in simple medical language.
  • This article explains Dosage in simple medical language.
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Definition

Allylestrenol is a . It derives from a hydride of an estrane.

A synthetic steroid with progestational activity. It is widely marketed throughout Europe, including Russia and many other European countries, and is also available in Japan, Hong Kong, India, Bangladesh, Indonesia, and much of Southeast Asia, though notably not in the United States or Canada. A synthetic steroid with progestational activity.

Allylestrenol is a progestogen structurally related to progesterone that has been given in threatened and , preventing . However, with the exception of proven progesterone deficiency, such use is no longer recommended. In threatened miscarriage, in progesterone-deficient women, a suggested dose is 5 mg three times daily by mouth for 5 to 7 days.

Mechanism of Action 

Allylestrenol is similar in structure and function to progesterone. Progesterone shares the pharmacological actions of progestins. Progesterone binds to the progesterone and estrogen receptors. Target cells include the female reproductive tract, the mammary gland, the hypothalamus, and the pituitary. Once bound to the receptor, progestins like Progesterone will slow the frequency of release of gonadotropin-releasing hormone (GnRH) from the hypothalamus and blunt the pre-ovulatory LH (luteinizing hormone) surge. In women who have adequate endogenous estrogen, progesterone transforms a proliferative endometrium into a secretory one. Progesterone is essential for the development of decidual tissue and is necessary to increase endometrial receptivity for the implantation of an embryo. Once an embryo has been implanted, progesterone acts to maintain the pregnancy. Progesterone also stimulates the growth of mammary alveolar tissue and relaxes uterine smooth muscle. It has little estrogenic and androgenic activity.

It exhibits trophoblastic, planktotrophic, and β2-adrenergic activity with no androgenic action. Allylestrenol stimulates the hormonal effects of existing syncytiotrophoblast which are necessary for progesterone production. The pregnancy-maintaining effect is due to the stimulation of the placental function, and the stimulation of β2-adrenergic receptors prevents uterine contractility.

Indications

  • Allylestrenol was designed to be used for miscarriage prevention, and prevention of premature and has been investigated for possible use in men for treatment for prostatic hyperplasia.
  • Allylestrenol is used in the treatment of recurrent and threatened miscarriage and to prevent premature labor.[rx][rx] However, except in the case of proven progesterone deficiency, its use for such indications is no longer recommended.[rx] Allylestrenol is one of only a handful of progestogens that has commonly been used for such purposes, the others include progesterone, hydroxyprogesterone caproate, and dydrogesterone.[rx] The medication has also been studied in the treatment of gynecological disorders such as , irregular menstruation, and premenstrual .[rx] Unlike other progestins, allylestrenol has not been used in hormonal  or in menopausal hormone therapy. In one study, it was found to be inadequate for endometrial transformation in women in combination with estradiol valerate.[rx] On the other hand, allylestrenol was found to be effective in the treatment of hot flashes in postmenopausal women.[rx]

What is it prescribed for?

  • Premature labor
    Allylestrenol is used in the prevention of pre-term , a condition where the body gets ready to give birth much earlier than the expected due date.
  • Miscarriage
    Allylestrenol is used to prevent miscarriage which is the spontaneous loss of the foetus and termination of the pregnancy within the first 20 weeks.
  • Habitual abortion
    Allylestrenol is used to prevent habitual abortion, a condition with three or more consecutive pregnancy losses or miscarriages occur.
  • Intrauterine growth retardation
    Allylestrenol is used to treat intrauterine growth retardation, a condition where the developing baby or foetus is not growing at the normal expected rate.
  • Failure of nidation
    Allylestrenol is used to treat the ‘failure of nidation’, a condition where the embryo fails to implant in the .

Contraindications

  • Diabetes
  • Excessive fat in the blood
  • Porphyria
  • Overweight
  • Depression
  • Poor Vision
  • Optic Disk
  • High blood pressure
  • Lung
  • Stroke
  • Obstruction of a Blood Vessel by a Blood Clot
  • Blood Clot in
  • Problems
  • disease with a reduction in kidney function
  • seizures
  • Visible water retention
  • Pregnancy
  • Increased cardiovascular event risk

Threatened miscarriage

  • Adult: 5 mg tid for 5-7 days, treatment may be prolonged if necessary. Gradually reduce dosage if symptoms disappear.

Oral
Recurrent miscarriage

  • Adult: 5-10 mg daily as soon as pregnancy is confirmed. Continue treatment for at least 1 month after the critical period.

Oral
Premature labor

  • Adult: For threatened premature labor: Individualise dosage. Max: 40mg daily.

Missed Dose

Take the missed dose of Allylestrenol as soon as you remember. If it is almost time for your next dose, skip the missed dose. Do not double your dose to make up for the missed one.

Overdose

Seek medical treatment in case of a suspected overdose of Allylestrenol.

Side effects

Most common

  • Weight gain
  • Change in appetite
  • Fluid Retention
  • Edema
  • Skin
  • Depression
  • Headache
  • Changes in libido

Common

Less common

  • Abnormal dreams
  • change in sense of taste
  • congestion
  • discouragement, feeling sad, or empty
  • Acting on dangerous impulses
  • Aggressive or violent behavior
  • Thoughts about suicide or dying
  • New or worse depression
  • New or worse anxiety or panic attacks
  • Agitation, restlessness, anger, or irritability
  • Trouble sleeping
  • An increase in activity or talking more than normal

Drug Interactions

Allylestrenol may interact with the following drugs, and supplements & may decrease the efficacy of the drug

  • Bivalirudin
  • Leuprolide
  • Goserelin
  • Desmopressin
  • Daptomycin
  • Cyclosporine
  • Octreotide
  • Cyanocobalamin
  • Folic acid
  • Calcitriol
  • Pyridoxine
  • Vitamin E
  • Pyridoxine
  • Fluvoxamine
  • Flunisolide
  • Baclofen
  • Amphetamine
  • Lorazepam
  • Bortezomib
  • Tramadol
  • Fluconazole
  • Oseltamivir
  • Erythromycin
  • Hydroxocobalamin
  • Azithromycin
  • Pantoprazole
  • Citalopram
  • Lovastatin
  • Pregabalin

Pregnancy and Lactation

Pregnancy

Allylestrenol is considered safe for use if you are pregnant. All the risks and benefits should be discussed with your doctor before taking this medicine.

Breast-feeding

Allylestrenol is not recommended for use in your breastfeeding as it may harm your infant.
General warnings

Kidney disease

Allylestrenol should be used with caution if you have kidney problems due to the increased risk of worsening your condition. Your doctor may adjust the dose of this medicine or prescribe a suitable alternative based on your condition.

Breathing disorders

Allylestrenol should be used with caution if you have a history of breathing disorders such as , emphysema, and chronic bronchitis, etc., due to the increased risk of worsening your condition.

Loss of vision

Allylestrenol should be discontinued immediately if you experience any vision loss, proptosis, or diplopia. Inform your doctor if you experience any side effects like blurred vision or excessive drying of the eyes. Do not perform activities such as driving vehicles or operating machines if you experience these symptoms.

Depression

Allylestrenol should be used with caution if you have a history of depression due to the increased risk of worsening your condition. Any change in behavior or mood should be reported to your doctor on priority.

Use in children

Allylestrenol is not recommended for use in children under the age of 16 years as the safety and efficacy of use are not clinically established.

Operating machines and driving vehicles

Avoid performing activities that require high mental alertness such as driving vehicles or operating machines during treatment with Allylestrenol as this medicine may impair your ability to perform these tasks.

References

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  2. Step 2

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  4. Step 4

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  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

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