Magnesium Supplement

Hello Kate,

Thanks very much for getting in touch. My name is Helen, I’m one of the Cancer Information Nurses on the Macmillan Support Line.

Welcome to the online community.

You have explained that your mum suffered with sleep issues previous to her breast cancer diagnosis, but now has the added symptoms of restless legs and anxiety, which no doubt also worsens her sleep pattern.

You have researched these symptoms in relation to low levels of magnesium and wonder if they might improve with the use of a magnesium cream.

The cream that you linked has magnesium chloride as an ingredient, a type of salt that is found in products such as magnesium oils and some bath salts.

A paper published in 2017 suggests there is little evidence that the amount of magnesium absorbed from creams and salts transdermally, i.e. through the skin, has a benefit (scroll to the conclusion at the bottom of the paper for a brief precis). The researchers were not ruling it out, but stated the clinical evidence is thin and called for further investigation into the subject.

The cream that you linked looks like a lovely product and will smell gorgeous with the lavender. Lavender is an essential oil that is shown to be helpful for people struggling with sleep issues. But any sleep benefits of the cream are not likely to be due to its magnesium chloride content being absorbed to any therapeutic level.

Also there are several types of medications that have the potential to interact with magnesium supplements. One is a bone strengthening drugs called a bisphosphonates. Some women on breast cancer therapy need to take a bisphosphonate to protect their bones, and your mum may be prescribed this.

So it’s also important that she doesn’t take any over-the-counter magnesium supplements without reference to her GP or her breast cancer doctor first.

Generally, the NHS advocate we get our vitamins and minerals from our diet rather than through supplements. Here is a list of magnesium-rich foods that might be useful to be aware of.  

I am popping a link to the charity Restless Leg Syndrome UK. They state that RLS can cause both insomnia and anxiety. They have lots of helpful advice on managing symptoms (I must admit, they do state that magnesium sprays have helped some users) but also make a good case for the GP eliminating underlying causes, such as anaemia.   

You also mentioned your mum has irritable bowel syndrome. It’s possible with flare ups of this condition that your mum doesn’t absorb necessary minerals, such as iron and magnesium. Another reason for her to speak to her GP. 

You mentioned that your mum is taking medication as part of her ongoing treatment, but you didn’t specify what that might be. She may be taking an anti-hormone drug such as anastrozole. It’s worth saying that anti-hormone treatment can cause insomnia and anxiety as well.  

In summary, it’s important that either your mum’s breast cancer team, or her GP is made aware of her new, and worsening symptoms. These might be due to a mineral deficiency, such as a magnesium, but it’s always best for this to be investigated and treated in the context of her other diagnoses and medication.

Here is Macmillan’s information on coping with insomnia and with anxiety. You might also encourage your mum to take up our offer of four free counselling sessions, which focus on ways to manage worry. 

In addition, you might consider giving us a call, Kate. We would be very pleased to chat through the concerns you have about your mum and to support you to support her. Do give us a call if you think that would be helpful. Alternatively, you can contact us via email or webchat for further information or support.

The Macmillan Support Line offers practical, clinical, financial and emotional support. You can call us free from landlines and from most mobile phone networks on 0808 808 00 00, 7 days a week, 8am – 8pm.

Best wishes, Helen

Cancer Information Nurse Specialist 

Ref HM/DS