Conjugated Estrogens (Oral)

Conjugated estrogens are used in the treatment of menopausal symptoms and hypoestrogenism in women.


Conjugated estrogens are a hormonal treatment that is used to manage menopausal symptoms and hypoestrogenism in women. Problems that are treated with this medication include changes in and around the vagina, and hot flashes. Conjugated estrogens are also very useful in the prevention of bone thinning conditions such as osteoporosis that affect some women following the menopause.

Your doctor may also give you a prescription for conjugated estrogens to treat breast and prostate cancers that have spread. Some pre-menopausal women may also benefit from using this drug if their ovaries do not naturally make sufficient estrogen.

This medication comes in the form of tablets, and is sold under the brand name Premarin in the US.

Conditions treated

  • style="font-weight: 400;">hypoestrogenism
  • female menopause
  • 400;">breast cancer
  • prostate cancer

Type of medicine

  • estrogen hormone
  • tablet


In addition to its many benefits, conjugated estrogen tablets can bring some unwanted side effects. Not everyone will notice any side effects, but if they do occur, you might need to check with your GP.

There are a number of side effects that have been reported by users of this medication that always necessitate medical attention. See your doctor promptly if you notice any of the following effects:

  • wheezing
  • vomiting blood
  • vomiting
  • vaginal bleeding
  • unpleasant breath odor
  • trouble breathing
  • tightness of the chest
  • tender or painful cysts in the breasts
  • swelling, pain, or tenderness, of the legs or feet
  • swelling of the lips, hands, eyelids, face, or feet
  • swelling of the abdomen or stomach
  • sweating
  • sudden shortness of breath or breathing problems
  • stomach pains or upset
  • sour or acid stomach
  • sores on the breast that do not heal
  • 400;">sore throat
  • sneezing
  • slow speech
  • shortness of breath
  • severe, throbbing headache
  • runny nose
  • redness, pain, or swelling in the arm or leg
  • redness of the skin
  • reddening or swelling of the breasts
  • rectal bleeding
  • rash
  • problems with recognizing objects
  • problems swallowing
  • pressure in the stomach, or full or bloated feeling
  • persistent scaling or crusting of the nipple
  • pain or discomfort in the chest
  • pain in the side, stomach, and abdomen, sometimes radiating to the back
  • nausea
  • nasal congestion
  • 400;">migraine headache
  • lump under the arm or in the breast
  • loss of voice
  • loss of appetite
  • loss of ability to speak
  • lack of insight or judgment
  • joint stiffness, pain, or swelling
  • jaundice
  • itching
  • irritation
  • inverted nipple
  • 400;">indigestion
  • inability to move the facial muscles, arms or legs
  • hoarseness
  • 400;">hives
  • 400;">heartburn
  • 400;">fever
  • feeling unusually tired or weak
  • fast heartbeat
  • fainting
  • ear congestion
  • double vision
  • 400;">dizziness or lightheadedness
  • discomfort or pain in the arms, jaw, back, or neck
  • dimpling of the skin on the breasts
  • difficulty with speaking
  • difficulty with breathing
  • difficulty walking
  • difficulty planning and thinking
  • difficulties with memory or speech
  • 400;">diarrhea
  • dark urine
  • cough
  • 400;">constipation
  • confusion
  • clay-colored stools
  • chills
  • changes in skin color
  • change in vision
  • change in vaginal discharge
  • blurred vision
  • bloody stools
  • bloody or clear discharge from the nipples
  • belching
  • backache
  • anxiety
  • a feeling of pressure or pain in the pelvic area

There are a number of effects that sometimes occur in patients using conjugated estrogen tablets, which do not usually need medical treatment. These effects often go away on their own as your body gets used to the drug. Your GP or specialist may also be able to show you some ways of preventing or managing these more unpleasant effects. If you find that the effects do not go away within a week or so of starting your treatment with this medicine, or they are becoming very troublesome, have a chat with your GP.

  • white spots, ulcers, or sores in the mouth or on the lips
  • weight changes
  • unexpected or excessive milk discharge from the breasts
  • thick, white discharge from the vagina that has no odor or a mild odor
  • swelling or soreness of the breasts in both men and women
  • red, irritated eyes
  • rash
  • passing gas
  • painful, red lumps under the skin of the legs
  • painful sexual intercourse
  • pain in the knees or ankles
  • pain
  • muscle stiffness
  • mood changes
  • loss of scalp hair
  • loosening, blistering, or peeling, of the skin
  • leg cramps
  • lack of or loss of strength
  • joint or muscle pain
  • itching of the genitals or vagina area
  • irritability
  • increased in sexual performance, desire, or drive
  • increased facial hair growth
  • inability to obtain or maintain an erection
  • hives or welts
  • heavy bleeding
  • fall in libido
  • excess gas in the intestines or stomach
  • difficulty moving
  • diarrhea
  • 400;">depression
  • dark brown discoloration or brown patches on the skin
  • cramps
  • back ache

You may also notice a few side effects that are not already noted here. If you do, have a chat with your doctor or specialist.


You must only use your prescribed course of conjugated estrogens as you have been told to by your GP. Don't take more of the drug than you have been prescribed. Do not increase the frequency of use of the medicine or use it for a longer period of time than your treating physician ordered. Using too much of the medication could increase the side effects that it may cause.

When your pharmacist dispenses your medication, you will also be given an information leaflet. Read all the information and make sure that you understand it. If you have any queries, ask your treating specialist.

You may take your tablets with water or with a meal if you prefer. The drug will work better if you take the tablets whole, rather than chewing, sucking, or crushing them.

Try to include plenty of calcium and vitamin D in your diet or alternatively, take vitamin supplements. This is important to ensure that you have enough calcium in your body to protect you against bone thinning conditions.

The amount of conjugated estrogen tablets that you are told to take will vary between patients. Always do as your GP tells you to when taking the tablets or follow the instructions on the dispensary label. Do not change the dose, even if yours is different, unless your treating physician says that you should. Your dose and the number of tablets you take each day is calculated on the potency of the preparation you have been given and the reason you have been told to take the medication.

To prevent menopausal symptoms and osteoporosis:

Adults: Initially, take 0.3 mg daily in one dose. Your doctor may tell you to take this medicine for 25 days, followed by a five day period when you do not take it. Your GP might also change the amount of the drug you take, depending on how your body responds to treatment.

Children: If your doctor decides to prescribe this drug to your child, follow the instructions you are given.

To treat advanced prostate cancer:

Adults: Initially, take 1.25 to 2.5 mg daily as two tablets, in three doses, evenly spaced across each day.

Children: If your doctor decides to prescribe this drug to your child, follow the instructions you are given.

To treat breast cancer in both women and men:

Adults: Initially, take 10 mg thrice daily.

Children: If your doctor decides to prescribe this drug to your child, follow the instructions you are given.

To treat hypoestrogenism in women when caused by hypogonadism:

Adults: Initially, take 0.3 mg to 0.625 mg daily in one dose. Your doctor may tell you to take this medicine for 25 days, followed by a five day period when you do not take it. Your GP might also change the amount of the drug you take, depending on how your body responds to treatment.

Children: If your doctor decides to prescribe this drug to your child, follow the instructions you are given.

To manage hypoestrogenism following female ovarian failure or castration:

Adults: Initially, take 1.25 mg daily in one dose. Your doctor may tell you to take this medicine for 25 days, followed by a five day period when you do not take it. Your GP might also change the amount of the drug you take, depending on how your body responds to treatment.

Children: If your doctor decides to prescribe this drug to your child, follow the instructions you are given.

In the event that you forget a dose of your conjugated estrogen tablets, you should attempt to have it straight away. If the time of your usual dose is close, miss one out and revert to your regular schedule. You must not take two doses at any one time.

You must take your medication as prescribed in order to derive the best benefit from using it. This means that you should take your tablets at the same time every day. It is a good idea to note the usual dosage times on a calendar or in your diary to aid your memory. This is especially important if you are observing the 25 days on, five days off cycle.

If you think that you are actually feeling worse than you did before you started taking the medication, or if you think that you are not actually improving, have a chat with your doctor. Do not stop taking the medicine suddenly, unless your treating physician instructs you specifically to do so.


It is not advisable to use certain drugs together, because there may be an interaction between them. However, your doctor may decide to treat you with multiple medicines if it is deemed the best way to treat your condition. In such circumstances, you may have one or both of your doses adjusted. Your GP or treating specialist may offer you some advice on how to manage or prevent the effects of the interactions that may occur.

It is not advisable to take conjugated estrogens with Bupropion, Donepezil, or Dasabuvir.

Using conjugated estrogen tablets with any of the following medicines could cause side effects to be more likely, although using both medicines might be the best way of treating your health problem. You may find that your GP changes the dose of your medicines or tells you to take them more or less frequently.

  • Tipranavir
  • St John's Wort
  • Licorice
  • Levothyroxine
  • Ketoconazole
  • Ginseng
  • Etoricoxib
  • Clarithromycin

Some drugs must not be taken with food, or when drinking alcohol, or when using tobacco. Your GP will give you more advice on this.

If you are prescribed conjugated estrogen tablets, you should avoid eating grapefruit and drinking grapefruit juice.


If you have ever had an allergic or odd reaction to any prescription drugs or to any over-the-counter products, tell your GP. Similarly, if you know that you have allergies to certain food groups, food dyes, food preservatives, or animal derivative products, tell your doctor before you begin your course of treatment with this drug.

There are no specific known problems that are associated with geriatric patients who are using conjugated estrogens. However, elderly patients may be more vulnerable to conditions including, stroke, dementia, prostate cancer, and breast cancer. Therefore, conjugated estrogens should be used with caution in these patients.

If you are pregnant, or if you think that there is a chance you may be pregnant, you must tell your doctor immediately before you begin taking conjugated estrogens. These medicines can cause fetal abnormalities and death in unborn babies. You are strongly advised to use effective contraception during the time you are taking conjugated estrogens.

Research has shown that conjugated estrogens can make changes to milk composition or to levels of milk production. If you are unable to use an alternative medication and you are breastfeeding, you should keep a close eye on your infant to make sure that no side effects emerge and that you are producing sufficient milk for its needs. Speak to your midwife for advice on alternatives to breast milk for your child, and do not breastfeed until at least two weeks after you have stopped using conjugated estrogens.

Other health conditions can influence the effects of conjugated estrogens. You must tell your treating specialist if you have any existing or historical medical problems.

Conjugated estrogen tablets must not be used to treat people who have any of the following illnesses:

  • unusual or abnormal bleeding from the vagina
  • stroke
  • 400;">pulmonary embolism, deep vein thrombosis, or blood clots
  • 400;">liver disease
  • heart attack
  • estrogen-dependant tumors
  • breast cancer
  • blood clotting disorders, including protein S and protein C

Using conjugated estrogens in patients who have suffered from any of the following conditions may make their condition worse:

  • systemic lupus erythematosus
  • seizures
  • 400;">porphyria
  • migraine headaches
  • 400;">liver tumors
  • jaundice during pregnancy or from hormonal treatments
  • 400;">hypothyroidism
  • hypertriglyceridemia
  • 400;">hypertension
  • hypercalcemia
  • hereditary angioedema
  • heart disease
  • 400;">gallbladder disease
  • 400;">epilepsy
  • 400;">endometriosis
  • edema
  • diabetes
  • cancer
  • 400;">asthma

You must be sure to attend your GP or specialist regularly for check-ups. These visits are important to allow your doctor to make sure that the drug is fully effective and is not causing any undesirable side effects.

Your GP may want you to undergo certain tests, including breast examinations, pelvic examinations, and mammograms during your treatment with this drug.

Taking large amounts of conjugated estrogens over an extended timeframe can increase the danger of you having a stroke, dementia, certain cancers, heart attack, or blood clots.

If you still have your womb, you should ask your GP if it is also necessary for you to take a progestin hormone drug in addition to conjugated estrogens.

Conjugated estrogens can increase the risk of a stroke or of developing heart disease in people who smoke. There is also an increased risk of suffering from these conditions if you have high cholesterol, are overweight, or if you suffer from diabetes. Talk to your GP or local support network about ways to stop smoking and work hard to keep your diabetes controlled. You might want to consider changing your diet, taking more exercise, and taking steps to lower the amount of cholesterol in your blood.

If you are due to go into hospital or to the dentist for any form of surgical treatment, you must tell your treating physician that you are taking conjugated estrogens. The same applies if you are likely to be confined to bed or to a chair for any length of time, for example during a long-haul plane journey. These circumstances can make it more likely that you will develop a blood clot. Under these circumstances, you might need to stop taking your medication or take other precautions.

This medication can also alter the results of certain tests, so you must tell the nurse who is attending to you that you are taking it.

Using conjugated estrogens may make it more likely that you will get uterine cancer. If you experience any odd vaginal bleeding while you are taking this medicine, tell your doctor straight away.

If you notice any blotchy patches or areas of darkened skin on your face, you may be suffering from melasma as a result of taking conjugated estrogens. Exposure to bright sunlight can make this condition worse. Limit the amount of time you spend outside on sunny days and to not use sunlamps or tanning booths.

If you experience sudden headaches, loss of vision or visual disturbances after taking this medication, stop taking the tablets and tell your doctor straight away.

Some people have suffered a severe allergic reaction to conjugated estrogens. This reaction is called anaphylaxis, or sometimes it is referred to as anaphylactic shock. Anaphylaxis usually occurs within a few minutes of taking the medicine and it should always be treated as a medical emergency. If you develop any of the following symptoms immediately following your dose of medicine, call 911.

  • breathing problems
  • feeling that you cannot swallow
  • swelling around your mouth, tongue, or face


Keep your prescription of conjugated estrogen tablets in a sealed container. Do not get the tablets wet. Place the tablets away from heat sources and do not put them on a shelf where they could be in direct sunlight. Do not refrigerate or freeze the tablets.

Make sure that you put your tablets where children and pets cannot gain access to them. If a pet does eat some of your tablets, you should seek veterinary advice as soon as possible.

You should not use medication that has become out of date. Do not take tablets that appear damaged or are crumbly in texture. To dispose of unwanted tablets, wrap them in a sealed bag and place them in the bottom of your trash, where children and animals cannot easily reach them. Do not throw tablets down the drain or flush them down the toilet.


Conjugated estrogens are hormones that are used to manage symptoms that occur at the onset of and during the female menopause. Women who suffer from a lack of naturally produced estrogen in their body can also be treated with this medicine. Conditions such as osteoporosis, where the bones become thin and brittle often affect post-menopausal women, and conjugated estrogens can also be beneficial in treating this problem. Certain cancers, including prostate and breast cancer can be treated with conjugated estrogens.

Conjugated estrogens are undoubtedly very beneficial in treating hormonally affected conditions in both men and women. However, there are a lot of side effects that can affect some patients. Many historical and existing medical conditions can also react adversely to the use of this drug. For these reasons, it is extremely important that you keep all your check-up appointments with your doctor or treating specialist.

You may also need to attend your doctor or nurse for tests to make sure that the treatment is working properly and to allow for adjustments to the dose to be made if required.