If you are often tired, sleep poorly or struggle with muscle cramps, a magnesium deficiency may play a part. Magnesium is involved in hundreds of processes in your body, from your muscles to your nervous system. Yet a shortfall is easy to overlook.
In this article I am happy to share what I often see in practice. We look at the symptoms women recognise, at causes that are specific to women, and at an honest note about magnesium tests that you rarely read anywhere.
Because a normal result does not always mean everything is fine.
What are the symptoms of a magnesium deficiency?
A magnesium deficiency often shows up as vague, physical complaints that you do not immediately link to this mineral. Common signals are muscle cramps, fatigue, irritability and poor sleep. Heart palpitations and headaches can be part of it too, although every complaint has several possible causes.
The symptoms differ from person to person and are rarely clear-cut. That is why a deficiency is so hard to judge by feel.
Symptoms that women relatively often mention:
- Muscle cramps and twitches, especially in the calves or eyelids
- Persistent fatigue that does not go away with rest
- Irritability and inner restlessness
- Trouble falling asleep or staying asleep
- Heart palpitations or an irregular feeling around the heart
- Headaches or migraine that return more often
What makes it even more confusing is that many of these complaints fit other causes too. Fatigue, for example, can be linked to your iron, your thyroid or simply a busy stretch. So a magnesium deficiency is rarely the only explanation.
That is why I prefer to look at the whole picture rather than one isolated complaint.
If you recognise several of these signals at once, it can be worth having your levels checked. A conversation with your GP is always the starting point.
What causes a magnesium deficiency in women?
In women, a few specific factors often play a role. Long-term use of the pill, chronic stress, digestive problems and certain medications can affect your magnesium balance. Menopause can play a role too. None of these factors automatically leads to a deficiency, but together they raise the chance.
Your diet is the foundation, but not the whole story.
Factors that are more common in women:
- Long-term use of the pill or other contraception, which can shift the mineral balance
- Chronic stress, where your body seems to use more magnesium
- Digestive problems such as an irritable bowel, which can reduce absorption
- Long-term use of acid reducers, which can affect absorption
- Menopause, where complaints and hormonal shifts overlap
During menopause in particular it is hard to separate the causes. Fatigue can then come from hormones, stress or anaemia. In our article on being tired in menopause, stress or anaemia we go into this in more detail.
Other minerals deserve attention too. For example, read our guide on zinc deficiency in women and how to test for it.
How reliable is a magnesium blood test?
A standard blood test measures magnesium in your serum, the liquid part of your blood. The problem is that roughly 99 percent of your magnesium is not in your blood but in your cells and bones. As a result, a normal serum value can miss a shortfall in your tissues.
This is exactly the caveat that many providers leave out.
The intracellular magnesium test measures magnesium in your red blood cells and gives a better picture of your stores. No test is perfect, but this one can offer additional information that serum alone does not.
In practice this means you should not put too much weight on a single normal serum result. If that result does not match your complaints, it is worth looking further rather than dismissing your symptoms as imagined.
A good doctor weighs your result, your complaints and your lifestyle together.
| Test | What it measures | Strength | Limitation |
|---|---|---|---|
| Serum magnesium | Magnesium in the liquid part of your blood | Widely available and inexpensive | Often stays normal even when your tissues run low |
| Intracellular magnesium | Magnesium in your red blood cells | Gives a better picture of your body stores | Less widely available and no absolute certainty |
If you want your levels measured, look at the marker magnesium and the additional marker intracellular magnesium. Together they often give a fuller picture than serum alone.
What helps with a magnesium deficiency?
The foundation lies in your diet. Magnesium is found in wholegrain products, dark green leafy vegetables, nuts, seeds and legumes. By eating these regularly, you support your magnesium intake in a natural way. Supplements can sometimes help, but they are not needed for everyone.
So start with your plate before reaching for a jar.
| Food group | Examples |
|---|---|
| Wholegrain products | Wholemeal bread, oats, brown rice |
| Dark green leafy vegetables | Spinach, kale, chard |
| Nuts and seeds | Almonds, cashews, pumpkin seeds |
| Legumes | Black beans, chickpeas, lentils |
About supplements I can be brief: they can be useful, but more is not always better. Too much magnesium from supplements can cause complaints such as loose stools.
So discuss their use with your GP or pharmacist, especially if you take medication.
See your GP if your complaints persist, worsen or come with heart palpitations, severe muscle problems or confusion. A professional can judge whether further testing is needed.
Frequently asked questions
Can a magnesium deficiency always be seen in your blood?
Not always. A serum test can stay normal while your tissues still run low, because most magnesium sits in your cells and bones. An intracellular test can then offer additional information, although no test gives complete certainty.
Does the pill raise the risk of a magnesium deficiency?
Long-term use of the pill is sometimes linked to a shifted mineral balance. The evidence is not clear-cut, and it does not mean you automatically have a deficiency. If you are unsure, discuss this with your GP.
How long does it take to notice a deficiency?
That varies greatly from person to person and depends on your diet, absorption and any complaints. Some women notice something fairly quickly, others only after a longer time. Persistent complaints are a good reason to have your levels checked.
Having your magnesium levels measured
If you want to know how your magnesium and other values are doing, you can include this in a broader check. Our extended health checkup brings several values into view at once, so you have a fuller starting point for a conversation with your doctor.
Want to know more about vitamins and minerals? Read our pillar on testing vitamins and minerals in women and which blood values matter.
Sources
- Voedingscentrum. Magnesium. Accessed 2026.
- Gezondheidsraad. Dietary reference values for vitamins and minerals, 2018.
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Dietary reference values for magnesium, 2015.
- Cochrane Database of Systematic Reviews. Magnesium supplementation, review publications.
Every blood test result through Lunara includes a professional assessment by a BIG-registered doctor. For treatment decisions, discuss your results with your GP.
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