BMA Concise Guide to Medicine & Drugs

Conjugated Oestrogens

Brand name Premarin

Used in the following combined preparations Premique, Prempak-C


Drug group Female sex hormone and drug for bone disorders

Overdose danger rating Low

Dependence rating Low

Prescription needed Yes

Available as generic Yes


Preparations of conjugated oestrogens consist of naturally occurring oestrogens similar to those found in the urine of pregnant mares. Taken by mouth, they are used to relieve menopausal symptoms such as hot flushes and sweating, but are usually only advised for short-term use around the menopause and are not normally recommended for long-term use or for treatment of osteoporosis.

As replacement therapy, they are usually taken on a cyclic dosing schedule, in conjunction with a progestogen, to simulate the hormonal changes of a normal menstrual cycle. On their own, they are not recommended for women with an intact uterus. They are also available as a vaginal cream to relieve vaginal or vulval pain and dryness after the menopause.

Conjugated oestrogens do not provide contraception. Pregnancy is still possible for 2 years after a woman’s last period (if she is under 50 years) or 1 year after the end of menstruation (if she is over 50).


Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets, cream.

Frequency and timing of doses Once daily.

Adult dosage range Replacement therapy 0.625–1.25mg daily (tablets); 1–2g daily (cream).

Onset of effect 5–20 days.

Duration of action 1–2 days.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember.

Stopping the drug Do not stop the drug without consulting your doctor because symptoms may recur.

Exceeding the dose An occasional unintentional extra dose is unlikely to be a cause for concern. But if you notice any unusual symptoms, or if a large overdose has been taken, notify your doctor.


The most common adverse effects are similar to symptoms that occur in the early stages of pregnancy, such as nausea, vomiting, breast swelling or tenderness, weight changes, and abdominal bloating or pain. These generally diminish or disappear after 2–3 months of treatment. The drug may also reduce sex drive. If headaches, migraines, depression, or vaginal bleeding occur, discuss with your doctor. If you develop jaundice, you should stop taking the drug and contact your doctor promptly. Sudden sharp pain in the chest, groin, or legs may indicate an abnormal blood clot that requires urgent medical attention.


Tobacco smoking

increases the risk of serious adverse effects on the heart and circulation with conjugated oestrogens.

Oral anticoagulant drugs Conjugated oestrogens reduce the anticoagulant effect of these drugs.


Be sure to tell your doctor if:

· You have heart disease or high blood pressure.

· You have had blood clots or a stroke.

· You have porphyria or diabetes.

· You have a history of breast disease.

· You have had fibroids in the uterus or abnormal vaginal bleeding.

· You suffer from migraine or epilepsy.

· You have long-term liver or kidney problems.

· You are taking other medicines.

Pregnancy Not prescribed. May affect the baby adversely. Discuss with your doctor.

Breast-feeding Not prescribed. The drug passes into the breast milk and may inhibit its flow. Discuss with your doctor.

Infants and children Not prescribed.

Over 60 No special problems.

Driving and hazardous work No known problems.

Alcohol No known problems.

Surgery and general anaesthetics Conjugated oestrogens may need to be stopped several weeks before you have surgery. Discuss with your doctor.


Conjugated oestrogens are normally only recommended for short-term use around the menopause. Long-term use may increase the risk of breast cancer, venous thrombosis, heart attack, and stroke.

Monitoring Regular physical examinations (e.g. mammograms) and blood pressure checks are advised.