Oestradiol comes in preparations designed for  systemic absorption (made to be absorbed into the general bloodstream to help with menopause symptoms like flushes, brain fog for example) and topical vulvovaginal oestrogen cream designed for local absorption when applied to the genitourinary areas to help with vaginal dryness and menopausal urinary symptoms.  

Systemic preparations of oestradiol are in the form of oral tablets (like the Progynova brand), transdermal (skin) patches (like the Estradot brand), or transdermal gels (like the Estrogel brand). In women who have not had a hysterectomy, systemic oestrogens need to be used with a progestogen to protect the endometrium (lining of the uterus) from becoming thickened. 

Below, Dr Kate Rassie, an endocrinologist colleague  with subspeciality interest in women’s hormone health based in Melbourne (but with longstanding ties with ERH Associates!) discusses transdermal oestrogens in more detail, and in particular why dosages of transdermal oestrogen might need to be individualised.  

Why is transdermal oestrogen considered safer than oral?  

Transdermal oestrogen is associated with a lower clotting risk than oral.   

• Transdermal oestrogen is absorbed directly into the bloodstream, bypassing the digestive tract and liver. When oestrogen is taken as a tablet, liver clotting factors are activated, resulting in small increases in the risk of clot and stroke. This does not occur with transdermal oestrogen.  
• Transdermal oestrogen is thus considered safer for women with cardiovascular or clotting risks, and safe for those who suffer from migraines (in whom oral oestrogen may not be recommended).  

Are there other benefits of transdermal oestrogen? 

• Transdermal oestrogen may also be a better choice for libido. Oral (tablet) oestrogen increases the levels of SHBG (sex hormone binding globulin), which reduces the amount of free blood testosterone in the circulation. Transdermal oestrogen does not have this effect so might be better for libido than oral oestrogen for some women. 
• The long, slow, steady absorption afforded by transdermal oestrogen delivery can help to prevent day-to-day fluctuating symptoms, especially for those who have trouble remembering to take an oral tablet at the same time each day.    

What are the usual doses of transdermal oestrogen?

Estradot is the most commonly prescribed brand of patch in New Zealand, and is available in 25, 50, 75 and 100mcg patches. All of them are changed twice weekly, lasting 3.5 days (eg. apply Monday morning, change Thursday evening). All contain oestradiol, an oestrogen identical to the body’s own oestrogen. They should be placed on the lower half of the body, typically the lower abdomen or buttock; alternating sides of the body with each application. The patches are designed to withstand swimming and showering, providing they are not exposed to excessive heat (e.g. saunas) or left soaking for long periods of time. The patches can also be cut, meaning that (if your ideal dose falls somewhere between the manufactured doses) you can make up a dose using half-patches. This has also been advised during patch shortages over recent months.  

Estrogel also contains oestradiol, but is dispensed via a pump bottle. The gel is applied daily in a thin layer to clean, dry skin: usual advice is to apply each pump across the whole surface area of an arm, “wrist to shoulder”. If two pumps are being applied, one pump should be applied to each arm. Women on one pump per day should alternate arms. The gel is given five minutes to dry before getting dressed. Other lotions and creams (such as moisturiser or sunblock) should not be applied for 60 minutes. One “pump” of Estrogel daily is considered broadly equivalent to a 25mcg patch (2 pumps to a 50mcg patch, 3 pumps to a 75 mcg patch, 4 pumps to a 100mcg patch). Women on 3-4 pumps per day may choose to split their dose between morning and evening applications.   In a general sense, 25 mcg (or one pump of gel) would be considered a “low” dose patch, 50mcg (or two pumps) a “mid” dose, and 75-100mcg (or three-four pumps) a “high” dose. However – unlike the dosing of many other medications we are familiar with – there is marked individual variation in a woman’s dose requirements

What influences the right dose for me? 

For women who go through menopause at the usual age of 45-55, the dose between 25-100mcg that is most helpful for your symptoms with no or minimal side effects is usually a good dose.  

This may vary from person to person.  One woman may start on a 25 mcg patch and have immediate relief from her hot flushes, but get side effects such as fluid retention and breast tenderness. Another woman may be on a 100mcg patch with no side effects, and no symptom relief either.  

There are two explanations for this variation.  

• Firstly, the absorption through the skin varies between women; so some women will need a higher patch dose to achieve similar circulating blood levels of oestradiol.  
• Secondly, even blood levels are not the whole story. Some women require higher oestradiol blood levels to activate their receptors – their tissues (bone, muscle, brain, breast) have different “oestrogen sensitivity”.  

As such, dose needs to be adjusted for each individual according to symptoms; and the right transdermal oestrogen dose for one woman may be too much (or not enough) for one of her peers.  

Doctors don’t routinely monitor blood levels of oestradiol in women taking MHT for menopausal symptoms – (a) because they vary significantly in a woman over time and according to when/ where a patch was applied; and (b) because a given blood level doesn’t always give us useful information about how the oestrogen is working to treat symptoms.  

However, occasionally, your treating doctor may check a one-off level (for instance, if they are worried you might not be absorbing your transdermal oestrogen sufficiently, in which case another formulation may be trialled). Some women may get better absorption from a patch than a gel, or vice versa. Occasionally, poor transdermal absorption across delivery methods might warrant a trial of oral oestrogen instead.  

Dr Kate Rassie is an endocrinologist at Jean Hailes Clinic in Clayton, with a subspecialty interest in women’s hormonal health. She believes in medicine that is evidence-based and holistic, acknowledging social and psychological complexity. 

Kate graduated from the University of Auckland in 2012 and completed her physician training in Auckland and Melbourne. Dr Kate is currently undertaking PhD studies at Monash Centre for Health Research and Implementation (MCHRI), Monash University. She also works clinically as a consultant endocrinologist in the diabetes unit at Monash Health. 

Find out more about Dr Rassie here: https://www.jeanhailes.org.au/team/dr-kate-rassi 

For more comprehensive menopause support, join the waitlist for our upcoming Menopause app-based course. The course will provide step-by-step guidance, evidence-based medical information mindset strategies, and practical tips to help you navigate menopause with confidence. We will be announcing the course launch date soon! 

For personalised medical care around the hormonal aspects of menopause ask your doctor for a referral to ERH Associates