If you’re aged 50 or older, menopause is defined as the permanent cessation of menses (periods) for at least 12 months. As menopause can’t be confirmed until you’ve not had a period for one year, the diagnosis has to be made retrospectively.

Menopause is a normal biological process. The average age we experience it in the Western world is 51. It occurs when levels of oestrogen, progesterone and testosterone are low, and the function of the ovaries has declined so that an egg is no longer released each month. 

Menopause can sometimes happen at a much younger age, and around 5% of the population will go through it before the age of 45. In 1% of people, it occurs before the age of 40. This is called early or premature menopause.

While menopause can be confirmed after 12-24 months without a period (12 months if you’re over 50, 24 months if you’re under 50), perimenopause is not so clearly defined. This can make it harder to diagnose. Perimenopause begins when the function in your ovaries starts to decline, and hormone levels start to fall. During this transition, you may notice that your periods become increasingly irregular until your cycle eventually stops completely. Perimenopause can be thought of as the time between your regular menstrual cycle (aka fertile years) and menopause (where fertility drops off).

The most common age for perimenopause to start is 47, and, on average, it lasts around four years. However, some people can experience symptoms of perimenopause for a decade or more. The timing and duration of perimenopause can be impacted by a number of factors:

• How old you are when perimenopause starts – onset at a younger age may mean perimenopause lasts for longer
• Genetics - the age your mother started perimenopause impacts the age at which you will likely also experience it
• Ethnic background – on average, black females reach perimenopause 8-9 months earlier than white females
• Body mass index (BMI) – a higher BMI can mean the transition to menopause starts later
• Smoking - if you smoke, perimenopause is likely to start up to two years earlier than in people who don’t smoke

Perimenopause can be a difficult time for many of us, regardless of whether we’ve had PMS or PMDD earlier in life. With diminishing ovarian function, oestrogen and progesterone production becomes erratic, making the levels of these hormones unstable. This can lead to symptoms including

• Irregular, heavier periods
• Night sweats
• Hot flashes
• Vaginal dryness
• Depressed mood
• Anxiety
• Difficulty concentrating
• Weight changes or changes in appetite
• Sexual changes, including finding sex painful or loss of libido
• Changes to sleep patterns, from insomnia to sleeping too much
• Lower energy levels
• Lack of interest in work, activities or hobbies

For those who have PMS or PMDD, the similarities between PMS and perimenopause can make it hard to work out which one is causing your symptoms.

Paying close attention to how you feel, and when, can help you work out if you are experiencing PMS or perimenopause.

In PMS and PMDD, symptoms typically worsen a week or two before the period. The exact cause of this is still not fully understood, and there are a number of theories about the causes, but there are strong links between PMS/PMDD and fluctuating hormone levels (particularly progesterone) that occur after ovulation and our individual sensitivity to such. Within a few days of your period arriving, hormone levels stabilise, and the symptoms of PMS/PMDD disappear.

In perimenopause, hormone levels fluctuate unpredictably rather than following a cyclical pattern. This means symptoms may be persistent or constant, or may seem to occur at random. For those who have a history of PMS or PMDD, the symptoms of perimenopause may feel particularly intense, and those symptoms previously experienced solely in the luteal phase may occur more frequently and erratically.

If you already have PMS or PMDD, it might be frustrating to learn that perimenopause can make PMS worse. This could be due to a number of reasons linked to the different causes of PMS/PMDD. One particularly likely cause is that people with PMS/PMDD might be more sensitive to hormonal changes in general. During perimenopause, our hormone production levels are starting to wane. This means that, when our hormones fluctuate during perimenopause, we’re just as likely to experience the effects as with PMS/PMDD, but because the ups and downs of oestrogen and progesterone can be more severe in perimenopause, this can make the symptoms feel stronger.

It could mean that for someone who has PMS/PMDD, their experience moving into menopause might be more challenging than for someone who has never had PMS or PMDD.

If you’ve already spent many years managing PMS or PMDD, you’ve probably got a good idea of what works to ease the symptoms. This might include leaning on friends or your partner for support, eating well, or gently exercising. You can take this knowledge with you into perimenopause to help ease the symptoms you experience. Although, it’s important to note that entering perimenopause may also upset any strategies you’ve already put in place for managing PMS because of the potentially random and unpredictable timings of symptoms (making them harder to predict and combat).

Regardless of whether you have been formally diagnosed with PMS or PMDD, you may benefit from talking to your doctor about PMS and perimenopause treatment. In some cases, hormone replacement therapy (HRT) may be offered to steady your hormone levels, preventing the peaks and troughs that cause symptoms.

Despite never having it before, some people experience PMS or PMDD for the first time when perimenopause begins, going through multiple symptoms occurring as a result of changing hormone levels.

If PMS or perimenopause symptoms are affecting your physical health, mental wellbeing, or quality of life for the first time, speak to your GP. They may offer you advice on lifestyle adjustments or medical treatments that can help you manage new-onset PMS.

When you go through perimenopause, your GP may prescribe hormone replacement therapy (HRT). As its name suggests, HRT is prescribed to replenish the body’s natural hormones and is usually given through a combination of different types of oestrogen and progesterone. HRT aims to smooth hormone levels out, avoiding the erratic highs and lows associated with perimenopause.

In some people, taking HRT can trigger PMS or PMDD symptoms. This is because PMS/PMDD are likely thought (amongst other things) to be triggered by progesterone. Sometimes, progestogen (a synthetic variation of progesterone, which has the same effect) is used in HRT. The symptoms triggered by progestogen are therefore labelled ‘progesterone-induced premenstrual disorder’, which is a form of PMS. If you think HRT has caused you to develop PMS or PMDD, speak to your doctor for advice.

Although menopause will eventually occur in everyone who experiences menstrual cycles, if you have severe PMS or PMDD, your doctor may have recommended ‘false’ menopause as a treatment option. The body can be put into a menopausal state using medication or surgery.

Medical, or chemical, menopause occurs when a gonadotropin-releasing hormone agonist (GnRHa) is given. Treatment with a GnRHa is offered to some people with PMS or PMDD because the drug temporarily switches off the ovaries and stops the body from releasing oestrogen and progesterone. This imitates the low hormone levels naturally associated with menopause, thereby preventing cyclical hormonal changes and the symptoms of PMS/PMDD.

Surgical menopause occurs when the ovaries are surgically removed during an operation called an oophorectomy (this is sometimes accompanied by removal of the uterus, cervix, and fallopian tubes, too). Because the ovaries produce oestrogen, removing them prevents oestrogen production, thus stopping the menstrual cycle. This therefore also prevents the symptoms of PMS/PMDD occurring. 

Often, people who are in chemical or surgical menopause are offered HRT to keep hormone levels steady and to provide additional long-term protection for bone, heart and brain health. Although it may take a few months to get used to HRT, once hormone levels settle, PMS and PMDD symptoms should no longer occur.

If perimenopause has affected or caused PMS or PMDD, various management options are available ranging from medical treatments to lifestyle changes, supplements to alternate therapies. A healthcare professional can help recommend the right treatment or support for you.

The good news is that once you are through perimenopause and into menopause, PMS and PMDD will no longer occur (as, regardless of which theory on the causes of PMS/PMDD may be true, there are no longer cycling levels of oestrogen and progesterone in the body).

Despite some of the bad press menopause gets, we might even be able to look forward to this part of our lives thanks to the freedom from PMS/PMDD it brings.