Hormone replacement therapy (HRT) side effects

HRT side effects are usually mild, but everyone experiences different ones. Most of the time, which side effects you experience when taking HRT depends on the type you are on, such as:

• HRT containing both oestrogen and progesterone
• oestrogen-only HRT
• continuous HRT (taken continuously, for menopause)
• sequential HRT (taken to mimic the natural cycle, for perimenopause)

Common side effects of HRT

Here is an overview of some of the most common side effects across all HRT treatments.

Gastrointestinal symptoms

When taking HRT, you may experience stomach pain, bloating, nausea, or you may even vomit.

Clinical studies have found a link between gastrointestinal side effects and HRT, particularly if you have been taking it for a long time. Usually, this tends to pass as your body adjusts to the treatment.

Swollen ankles and legs

Swollen ankles or legs are a frequently reported side effect of taking HRT. It’s also known clinically as peripheral oedema. It happens because of fluid retention as a result of hormonal changes that occur during hormone therapy.

This is typically more common among HRT medications that contain higher doses of oestrogen. If you find that this side effect persists, you should speak to your doctor.

Headaches

Experiencing headaches and migraines is a very common issue among women going through menopause, or those who are also taking HRT. A clinical study on 1,000 women found that this typically happens due to a sensitivity to hormonal changes, particularly fluctuations in oestrogen levels.

Sometimes women also experience aura or floating lights in their vision with headaches during HRT. If you find yourself having headaches often when taking HRT, or if you already get migraines and think you are starting menopause, speak to your doctor.

Thrush

Vaginal thrush is more common in women going through menopause or on HRT. Clinical studies have found that thrush happens more often when oestrogen levels are high, or when oestrogen levels are fluctuating because excessive oestrogen production causes the fungus that creates thrush to evade the immune system.

If you are experiencing recurrent thrush on HRT, including other symptoms like itching, burning, or unusual discharge, you should talk to your doctor. It may be the case that you need an alternative treatment.

Tiredness

If you are feeling more tired since taking HRT, this is very common, and it is usually down to changes in progesterone levels. This should go away as your body adjusts to HRT. However, if you find yourself experiencing fatigue for long periods, you should speak to your doctor as they may suggest an alternative HRT treatment.

Weight gain

Changes in the body during or after menopause are very common. Clinical studies have shown that changes to body composition and body shape also happen during this period. Weight gain is often caused by fluctuations in hormones that cause an increase in cravings and reduced energy.

If you are concerned about weight gain during your HRT treatment, speak to your doctor – they may suggest weight loss treatment or lifestyle changes as your body adjusts to ‘the change’ or hormone replacement therapy.

➤ You can find a more detailed list of side effects in your patient information leaflet, or by visiting the product page for the HRT available at ZAVA:

• Gina
• Elleste Duet (Conti)
• Estriol Cream
• Evorel Conti
• Tibolone
• Vagifem

Different doses of oestrogen and progesterone are available in HRT medications. You may find that certain side effects are caused by one or the other. Here is an overview of what side effects may be caused by oestrogen or progesterone.

Oestrogen side effects

High or fluctuating levels of oestrogen can cause:

• leg cramps
• water retention and swelling
• vaginal thrush
• vaginal bleeding or spotting
• hair loss

Progesterone side effects

High or fluctuating levels of progestogen may result in:

• changes in periods
• tiredness
• acne

Effects of both oestrogen and progesterone

Sometimes the effects of oestrogen and progesterone combined can result in certain side effects on the body, such as:

• headaches
• breast tenderness
• diarrhoea
• feeling sick (nausea)
• mood changes

You will typically be prescribed continuous HRT treatment if you are going through the menopause, whereas if you are perimenopausal (about to go through the menopause), you will likely be prescribed sequential HRT.

The key difference between continuous and sequential HRT side effects is how often you will bleed. Here is an overview comparison of common side effects in continuous vs sequential HRT:

How long side effects of HRT may last can vary. They tend to go away as your body adjusts to the treatment, with continuous combined HRT treatment, this can take between a few weeks and up to 3 months.

Due to the hormonal fluctuations of both oestrogen and progesterone, you may experience more side effects when taking sequential HRT.

If you experience any persistent side effects or have effects which are affecting your day-to-day life, you must speak to your doctor. There are a range of options when it comes to HRT treatments, so they may suggest an alternative.

If you experience common side effects of HRT within the first few months of treatment, you should be able to manage the symptoms at home as your body adjusts to HRT. Find out more guidance on this in the ‘Managing HRT side effects’ section of this guide.

If you find your symptoms become unmanageable or they begin to persist, you must speak to your doctor or pharmacist.

In the case that you experience any of the following rare or serious side effects, you must speak to a doctor as soon as possible, or call 999 in an emergency:

• pain, redness or swelling in one of your legs
• changes in vaginal bleeding after more than a few months of taking HRT
• a lump or changes in your breasts, dimpling of the skin, or changes in the nipple
• pain in the chest and breathlessness
• difficulty speaking or moving your arm or leg
• facial numbness and drooping on one side
• swollen tongue, lips, throat, and mouth
• tightness in the throat
• fainting
• sudden confusion or dizziness
• skin turning pale

There are a few ways you can avoid side effects of HRT, but first, it’s important to speak to your doctor about any concerns before you start your treatment.

Dosage and delivery

When avoiding side effects of HRT, you should consider your dose, and whether you will be taking your HRT by the mouth or via a patch, gel, or spray.

Some people prefer to take HRT locally, for example, to apply patches or gels. If you are sensitive to oestrogen, you may want to ask your doctor about a lower dosage of it in a combined treatment.

Taking your medication at the same time each day also helps to avoid irregular fluctuations of hormones that cause side effects when taking HRT.

Lifestyle

Lifestyle changes can help some women avoid side effects, including:

There are a variety of ‘natural’ remedies available for menopausal symptoms available over-the-counter. These remedies are known to have properties that may help balance fluctuating hormone levels. These include:

• evening primrose oil
• black cohosh
• ginseng
• St John’s wort
• angelica
• red clover

There is no medical evidence to support the idea that HRT causes weight gain.

If you're gaining weight around the time of your menopause this could be a natural result of ageing. As we age our metabolic rate slows and we burn calories less efficiently. There is a natural redistribution of body fat. Some of it moves to sit around the abdomen rather than on the hips. This is part of a natural ageing process.

We also start to lose muscle mass. As the muscle mass goes down, this reduces the metabolic rate further. Doing exercise and building muscle is an important way to help maintain your weight and health.

HRT could actually indirectly make it easier to manage your weight. Within a few months of starting you should find that your hot flushes and night sweats are much improved. As a result, you could be sleeping better, have more energy, and feel more like your normal self. This can help to address your diet and fitness.

As your body adjusts to HRT treatment, it’s common to experience some side effects. These side effects should go away after a few months at the most. In the meantime, there are ways you can minimise any pain or discomfort at home for common side effects.

Gastrointestinal symptoms

When taking HRT, you may experience gastrointestinal symptoms like stomach pain, bloating, nausea, or vomiting. To ease these symptoms, we recommend:

• eating lighter meals
• avoiding heavy, spicy or fatty foods
• drinking plenty of clear fluids
• taking HRT with food, if you’re taking it orally

Swollen ankles and legs

If you are experiencing high fluid retention as a result of taking HRT and are therefore finding your ankles and legs are more swollen than usual, this is common. To help with this, we recommend:

• light exercises such as walking, stretching, yoga, and swimming
• elevating your legs when resting
• wearing comfortable and loose-fitting trousers, socks, and shoes

Headaches

Headaches are a common side effect of the menopause. If you need relief from headaches or migraines with aura, take painkillers like paracetamol or ibuprofen. If this persists or you already had migraines before taking HRT, contact your doctor. They may suggest an alternative treatment for your menopause symptoms or a migraine treatment.

Thrush

For thrush, there are a range of treatments available which you can take alongside HRT. At ZAVA, you can choose a suitable remedy for thrush by browsing the Thrush Treatment service page. You can also request a consultation to find out which may be most suitable for you. If you get recurrent thrush while taking HRT, you should speak to your doctor.

Tiredness

Tiredness when taking HRT can sometimes be caused by fluctuating hormone levels. For the most part, this is caused by progesterone. To manage this symptom, we recommend good sleep hygiene, which includes:

• avoiding stimulants like screens and caffeine before bed
• setting a bedtime routine
• trying relaxation techniques in the evening

We also recommend exercising, which can increase your energy levels and improve your sleep at night.

You should track your sleep and how often you feel fatigued. If it persists, there could be an underlying reason, so you should monitor this and speak to your doctor if it begins to affect your daily life.

Weight gain

Weight gain can be a side effect of HRT and the menopause generally. Oestrogen fluctuations can be a cause of weight gain, or you may also be experiencing an increased appetite while taking HRT.

There are a range of ways to work on this and treat weight gain, including:

• regular exercise
• lifestyle changes, such as sticking to a balanced diet
• weight loss medication

Menopause is a normal, natural part of life which comes with changes in the body. If you feel that going on HRT is causing weight gain in addition to changes caused by the menopause in ways which may affect your health, you should speak to your doctor. They can suggest weight loss treatments or lifestyle changes suited to you.

Can HRT cause weight gain?

In some cases, the fluctuations in hormones when taking HRT, particularly oestrogen, can increase cravings. HRT can also cause fluid retention or bloating, which is sometimes mistaken for weight gain. Menopause itself can also cause weight gain due to the changes in the body as a result of adjustments in metabolism and hormone levels.

Clinical studies have found that some HRT treatments help to prevent weight gain. However, studies are limited, and HRT affects each person differently. If you are concerned about going on HRT because you feel it may make you gain weight, speak with your doctor.

Is HRT safe?

Yes, for the short term, HRT is safe and clinically proven to be an effective treatment for menopausal symptoms. There are some risks associated with taking it long-term. Although the risks are low, oral HRT tablets are associated with the highest risk of having blood clots and stroke. Combined HRT can also slightly increase the risk of breast cancer which increases the longer that you take it. There are lifestyle changes you can make alongside taking it that can lower this risk.

Just be sure to tell your doctor about any relevant current medical information or family medical history before requesting HRT. They’ll also monitor your progress and regularly review your treatment plan to make sure HRT continues to be safe and suitable for you.

What causes bleeding on continuous HRT?

Hormonal imbalances usually cause bleeding on continuous HRT. If you are taking continuous HRT and you experience bleeding, an excess of oestrogen without progesterone can lead to breakthrough bleeding. This can happen if you do not take your dose at the usual time, or if you miss your dose.

However, if you experience bleeding on continuous HRT, you should always raise this with your doctor. It may be the case that HRT has interacted with other medications you have taken, or your dosage may need to be adjusted. In rare instances, it can signal an underlying health condition, like endometrial or cervical cancer, or it could be a sign of fibroids, so it’s important to get this checked to be sure.

Do you still have periods on HRT patches?

Yes and no. HRT patches like Evorel Conti are not designed to cause bleeding like a period. This is because it contains continuous oestrogen and progesterone with no break, which prevents the shedding of the womb lining, so bleeding stops over time.

If you are on Evorel Sequi patches, you may experience a withdrawal bleed similar to a period because it works by mimicking your normal period – with the progesterone phase triggering a period-like bleed. This is not a period, and is a reaction to the drop in hormones.

Does HRT cause cancer?

HRT does not directly cause cancer, but it can slightly increase the risk of cancers like breast cancer. There is also a slight risk of womb cancer when taking HRT. There are lifestyle changes you can make while taking HRT to minimise the risk.