Possible Side Effects Of Hormone Replacement Therapy (HRT)

What can you do to manage HRT side effects?

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Medically reviewed by: Dr Kathryn Basford

Last reviewed: 30 Sep 2019

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Contents of this article

Hormone replacement treatment (HRT) has a lot of benefits, but side effects are possible too. The chance of side effects varies between different HRT methods so it's good to look into it before starting treatment.

Can HRT give me side effects?

There's a chance that HRT will give you side effects. The most common are:

  • feeling sick (nausea) – this can be reduced by taking your tablet at night with food
  • premenstrual symptoms
  • headache
  • breast tenderness and enlargement
  • skin irritation – this is more common with patches
  • acne or greasy skin
  • bloating
  • water retention
  • pain in the lower stomach
  • backache
  • leg cramps

Bleeding

Irregular vaginal bleeding/spotting is also common in the first three to six months on HRT. It often improves with time. You should discuss any bleeding with your doctor, as this may need investigating depending on what HRT you are taking, what the bleeding is like, and when you last had a bleed prior to HRT.

If you notice any new bleeding after not having had a period for more than six months, it’s important that you discuss this as soon as possible with your doctor.

What should I do if I get side effects?

Most often side effects are mild, and improve with time. Sometimes this is a reason to change the type of HRT you are taking, either the dose or the formulation. If you’re having HRT side effects, talk to your doctor. They will be able to check if your side effects are serious, and can give you advice about what to do.

Visit your nearest A&E department if you experience any of these rare but serious effects:

  • sudden increase in blood pressure
  • dizziness, confusion, or loss consciousness
  • sharp chest pain, sudden breathlessness, or pain and swelling in the legs – this could be a blood clot
  • chest pain radiating to the arms, face or jaw, fainting, shortness of breath – these are symptoms of a heart attack
  • sudden numbness of one side of the body, sudden trouble seeing, speaking, or walking, unexplained migraine-type headache with or without disturbed vision – this could be a stroke
  • face, mouth or throat swelling or difficulty breathing – this is likely to be an allergic reaction
  • yellow eyes or skin – this could indicate a liver problem
  • a rash (urticaria)

When else should I stop my HRT?

You should stop using HRT if you have:

  • a new diagnosis of breast or endometrial cancer
  • migraines, having never had them before
  • become pregnant

Can I tell if I will I get side effects before I start?

It’s not easy to predict if you will get side effects. Many women start HRT, feel better very quickly, and do not have side effects at all. But others do have side effects.

Can I do anything to avoid side effects?

In general, the following might help to lessen side effects:

  • take HRT as it has been prescribed, at the correct times of day, and do not miss out tablets or forget to change your patches
  • follow a healthy lifestyle: quit smoking, eat a healthy diet, drink alcohol within recommended limits, and take regular exercise
  • maintain a healthy BMI (21 to 25)

Take measures to minimise HRT symptoms like:

  • avoiding caffeine after 6pm
  • avoiding spicy foods/any food or drink that starts a hot flush
  • keeping the bedroom cool
  • wearing thin cotton layers
  • sleeping better by using dim lighting and having no electronic devices in the bedroom such as no TVs, laptops, or smartphones

Will I gain weight on HRT?

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.

Which HRT will give me the least side effects?

The following list shows which methods of HRT have more or less risk of side effects:

Less side effects:

  • HRT patches or gels
  • local vaginal HRT
  • oestrogen-only systemic HRT

More side effects:

  • combined systemic HRT
  • oral tablets

Oestrogen-only vs combined HRT

Oestrogen-only HRT side effects include:

  • feeling sick (nausea)
  • headache
  • breast tenderness

Oestrogen and progesterone combined HRT include the side effects above, plus:

  • depression
  • irritability – similar to having premenstrual syndrome
  • bloating

Oestrogen-only HRT oral tablets and patches are only meant for women who’ve had their womb removed – if you have not had your womb removed then you need to take both oestrogen and progesterone, or use oestrogen-only vaginal tablets. Oestrogen without progesterone can overstimulate the lining of the womb (the endometrium), giving a small increased risk of endometrial cancer.

With vaginal tablets or creams, the oestrogen does not reach the womb as easily so you don’t need progesterone as well.

Vaginal tablets, oral tablets, or patches and gels?

Vaginal tablets or creams are the least likely to give side effects because they do not enter the bloodstream as much (unlike oral tablets or patches).

Some women may find they have less side effects with patches and gels rather than oral tablets. This is thought to be because when using a patch, the hormones are being absorbed directly through the skin into the bloodstream.

With oral tablets, they have to be swallowed and absorbed in your stomach which can cause digestion problems.

Continuous vs sequential/cyclical

Continuous HRT treatment is less likely to cause bleeding-related side effects than sequential/cyclical treatment. This is because they work slightly differently:

  • continuous treatment is where you continue taking progesterone throughout your month’s cycle of HRT
  • sequential or cyclical treatment is where you only take progesterone for part of the cycle. You stopping taking it for two weeks during each month of HRT

Cyclical HRT is started if a woman is still having periods, and continuous HRT is used if the periods stopped more than a year ago, or after using cyclical HRT for more than one year.

Are there menopause treatments other than HRT that are less likely to cause side effects?

There are alternatives to HRT but in general, none of them work as well, and they’re not guaranteed to have fewer side effects.

Other medications

  • Some antidepressants – Selective Serotonin Reuptake Inhibitors (SSRI), including (fluoxetine, paroxetine, citalopram, sertraline) and the Serotonin Noradrenaline Reuptake Inhibitor/Selective Serotonin Reuptake Inhibitors (SSRI-SNRI), including venlafaxine which works to improve hot flushes and also any menopause-related (or non-menopause-related) depression or anxiety. SSRIs can also have side effects such as dizziness, dry mouth, constipation and reduced libido
  • Gamma aminobutyric acid (gabapentin) – this is a drug used to treat epilepsy. It can also be used to treat hot flushes, but may cause drowsiness. Some people like this as it may help them to sleep. However there may be side effects such as a dry mouth, dizziness and weight gain
  • Clonidine – this is a drug that is usually prescribed for high blood pressure but there is some medical evidence that it can improve hot flushes and night sweats

Cognitive behavioural therapy (CBT)

There is evidence to support the use of CBT to help alleviate menopausal symptoms. This treatment relies on a good understanding of menopause, relaxation techniques, better sleep, and a positive mental attitude. You may be referred for CBT by your doctor, or you can purchase a CBT guide to do this at home. CBT does not have side effects like medication does.

Herbal treatments

There are some herbal supplements that may improve menopause symptoms. They are likely to be less effective than HRT, or they may not work at all. They may or may not cause side effects even though they aren’t medication:

  • St John’s Wort – although this may help reduce hot flushes, it may interact with other medicines. St John’s Wort is not recommended for patients on tamoxifen as it can stop tamoxifen from working. If you’re taking St John’s wort, it’s important that you inform your doctor before you start a new treatment
  • Black cohosh (Cimicifuga racemosa) – this is one of the most frequently used herbal therapies for hot flushes. However, studies have not proven its efficacy, and there is very little known about its safety in clinical use. It may interact with other medicines. There have been anecdotal reports of liver failure
  • Isoflavones and red clover – these are plant oestrogens called ‘phytoestrogens’ which have oestrogenic effects in plants. They are found in high quantities in some foods, for example chickpeas, beans, soy beans, and tofu

Are there any other risks to HRT?

As well as side effects there are also risks to HRT treatment. There is an increased risk of breast cancer, heart disease, stroke, and blood clots

You should talk to your GP about these risks when deciding whether HRT is right for you. They will check how safe HRT will be for you and talk to you about any possible risks and benefits of the treatment.

Risk of breast cancer

There’s an increased risk of breast cancer on HRT. The Medicines and Healthcare products Regulatory Agency (MHRA) released a report in August 2019 with findings from new studies on these risks. These show that the risk is higher than originally thought. The MHRA's patient information leaflet covers this in more detail.

This is something that you should talk to your GP about at your next annual review. If you have any questions about this in the meantime, you can message our doctors through your account. They’ll be happy to answer any concerns you may have. You should also make sure that you’re going to your national breast-cancer screening appointments, and do the breast cancer self-checks as well.

Risk of stroke

Taking HRT tablets can slightly raise your risk of stroke (but the risk is not higher if you’re using patches or gels). There’s no proven increase in the risk of for women on HRT when it is started before 60 years old.

Blood clots

There is an increase in the risk of blood clots for women on HRT. This might be more related to tablets than patches, and mostly affects women who already have an increased risk of blood clots before HRT.

Risks linked to taking the treatment incorrectly

  • Overdosing – avoid any more of your HRT than you should. This can cause you to feel very sick
  • Not timing your bleed correctly (cyclical HRT only) – your bleed should happen when you start a new pack of your HRT. If it happens at other times you should talk to a doctor
  • Not changing patches at the right time (patches only) – you need to know how often they need changing and make sure you do it at the right time and in the right way. You should remove the old patch first and apply the new patch to clean dry skin
  • Swimming or sunbathing right after applying gel (gel only) – you need to wait for your gel to be absorbed first before doing these activities
  • Missing doses – missing doses here and there will not cause too much trouble but you may not have the best treatment effect, especially if you miss too many

What are the benefits of HRT?

  • Protection from osteoporosis (fragile bones). 1 in 2 women over 50 will break a bone because of osteoporosis (an osteoporotic fracture). Taking HRT will reduce your chance of an osteoporotic fracture by approximately 50%.
  • Less hot flushes/night sweats (5% of women have hot flushes for life)
  • Reduction in the risk of type 2 diabetes
  • A positive effect on collagen, the main constituent of skin, nails and hair, and of cartilage in joint spaces such as intervertebral discs, and helps joint pains
  • Improved symptoms of anxiety and depression
  • Reduced insomnia (sleeping problems)
  • Reduced vaginal dryness
  • Better tone of your pelvic floor which can help urge incontinence (bladder control) and reduce recurrent urinary tract infections
  • Better sexual function
  • Less problems with dry eyes
  • Possible protection against the onset of Alzheimer's and colonic cancer

Can you try HRT for a short time and then stop again?

You can start HRT and then stop, particularly if you’re worried about side effects. Remember that side effects may appear but they’re usually mild and go away over time. We recommend that you take treatment for at least 3 months, as long as you don’t have any serious side effects.

You can try more than one HRT method to find one that suits you – although this might take time and effort, it’s better than sticking with a treatment where you aren’t happy with the side effects.

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Medically reviewed by:
Dr Kathryn Basford

Dr Kathryn Basford is a qualified GP who works as a GP in London, as well as with Zava. She graduated from the University of Manchester and completed her GP training through Whipps Cross Hospital in London.

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Last reviewed: 30 Sep 2019

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