Can I take a sleep supplement with magnesium?

Before you combine a product sold for sleep with magnesium, ask a pharmacist or doctor, and show them every product and medicine you use. There are three reasons. Products sold for sleep contain many different ingredients and amounts, and the UK's NHS says some of those sold in pharmacies can make you drowsy. Magnesium may already be in more than one of your products. And the US upper limit for magnesium from supplements and medicines, published by the NIH Office of Dietary Supplements (ODS), is 350 mg a day for adults, while the Thai Reference Daily Intake (Thai RDI) for magnesium from all sources is 310 mg.

In short:

• First step: ask a pharmacist, with every product and medicine in hand
• Check the product sold for sleep: what is in it, and how much
• Add up the magnesium: from every supplement and medicine; the US upper limit for these is 350 mg a day
• If poor sleep goes on for months: see a doctor

This article is about putting products together. For habits that make it easier to fall asleep, see Can't sleep because your mind won't stop thinking?

Can I take a product sold for sleep together with magnesium?

There is no single answer that fits every product, because products sold for sleep contain many different ingredients and amounts. That is why the advice from public health bodies is the same each time: talk to a health professional first, and tell them everything you use.

What public health bodies advise

• The US Food and Drug Administration (FDA) says certain dietary supplements can change the absorption, metabolism or excretion of a medication, and that before you take any dietary supplement or medicine, it is important to discuss it with your health care professional.
• The ODS says you are most likely to have side effects from dietary supplements if you take them at high doses, instead of prescribed medicines, or if you take many different supplements.
• The National Institute on Aging (NIA) says that a product being called "natural" does not mean it is safe, and that a supplement might make a prescribed medicine weaker or stronger.

Questions to ask the pharmacist

The NIA's list of questions for a doctor or pharmacist includes whether a medicine will cause problems with other medicines or supplements you take, and whether it is safe to drive while taking it. For a product sold for sleep, you might ask:

• What is in this product, and is it a food or a medicine?
• Do any of my products contain the same ingredient, such as magnesium?
• Could any of them affect the medicines I take?
• Can I still drive or work with machines after using it?

What should I know about a product sold for sleep?

Side effects people may notice

The NHS says products you can buy from a pharmacy to help you sleep can have side effects; for instance, they may make you drowsy, which could make it difficult to do things like drive. It advises checking with your doctor before taking anything for sleep problems.

Products bought online or from abroad

A product bought online or carried back from abroad was made for another market. Take the package to a pharmacist and ask what each ingredient is before you use it.

Read the whole label

Look at the full ingredient list and the amount of each ingredient per serving, not only the name on the front. If the label lists minerals, note each amount so you can add them up with your other products.

How much magnesium is too much?

Food is not counted in the upper limit

The ODS says magnesium naturally present in food and drinks is not harmful and does not need to be limited, because in healthy people the kidneys get rid of any excess in the urine. The US upper limit of 350 mg counts only magnesium from supplements and medicines. The ODS says high intakes from these can cause diarrhoea, nausea and abdominal cramping.

Magnesium can be in more than one product

According to the ODS, magnesium is found in:

• multivitamin and mineral supplements
• other dietary supplements
• some laxatives
• some products for heartburn and indigestion

If you use a magnesium supplement, a multivitamin and any other product that lists magnesium, the amounts add up towards the same upper limit. The NHS says taking more than 400 mg of magnesium for a short time can cause diarrhoea, and the UK Department of Health and Social Care advises that you should be able to get all the magnesium you need from a varied and balanced diet, and that if you take magnesium supplements you should not take too much, as this could be harmful.

How common is poor sleep in Thailand?

Thichumpa and colleagues at Mahidol University, in a study published in 2018, interviewed 266 randomly selected people aged 60 and over in a rural subdistrict of Chiang Rai using the Thai version of a standard sleep questionnaire. 44.0% had poor sleep quality. The study covered one subdistrict, so the figure is not a national rate, and it describes older people rather than all adults.

How many Thai adults use supplements, and what do they want to know?

The surveys below asked about herbs and dietary supplements in general. They did not ask about products for sleep.

What these numbers can and cannot tell you

Neither survey chose people at random, and each covered one city, so the figures are not national rates. What they do show is that many people who use supplements say they would like more information on how they mix with medicines, which is the question to take to a pharmacist.

What should I bring when I ask a pharmacist?

One list of everything

The ODS suggests keeping a complete record of the dietary supplements and medicines you take, with each product's name, the dose, how often you take it and why. The FDA advises bringing a list of all the dietary supplements and medicines you take every time you visit a health care professional.

The products themselves

Bring the packages, including any product sold for sleep, any magnesium product and any multivitamin, so the pharmacist can read the full labels.

Tell them about your medicines and plans

The ODS says some supplements can change your response to anaesthesia if taken before surgery, so tell your doctor about them if you have an operation planned. The NHS notes that many medicines can affect sleep, which is another reason to bring your regular medicines.

When should I see a doctor about my sleep?

The NHS advises seeing a doctor if:

• changing your sleeping habits has not helped
• you have had trouble sleeping for months
• poor sleep is affecting your daily life in a way that makes it hard to cope

The NHS also advises not driving when you feel sleepy.

Who should talk to a doctor or pharmacist first?

People who take regular medication

The ODS says magnesium supplements can interact with or interfere with some medicines. If you take any medicine regularly, ask a doctor or pharmacist before adding magnesium or a product sold for sleep.

Pregnant and breastfeeding women

If you are pregnant or breastfeeding, talk to a doctor or pharmacist before taking any dietary supplement, including magnesium.

Dietary supplements are not intended to prevent, treat or cure any disease.