Keto Flu

 What is this “Keto Flu” that people talk about? How can you avoid it? What does it feel like? What do electrolytes do… and why do they matter? What supplements do you need on keto?

These questions are so frequently asked and the answers given swing to one extreme or the other or miss some of the electrolytes that people are likely to be low in. 

Keto flu symptoms are usually experienced in the first few days to weeks. Symptoms include headaches, nausea, grumpiness, feeling exhausted, slightly dizzy, upset tummy (or very infrequently actual vomiting), cramps and more! … But it can mostly be avoided! 

If you have an actual fever, sore throat, cough etc, this is not keto flu and if needed, see a doctor.

There are a few trains of thought around electrolytes and keto. We see many people who are successful with keto in our group Keto New Zealand and have seen the many ways that people handle electrolytes from never taking any to religiously taking them daily. We go down the middle route for electrolytes – Suggesting that people increase their electrolytes with keto but not as highly as some other Keto groups suggest. 

Keto is diuretic which means you pee out fluid rather than holding on to it. In the first few days especially of keto, you will be letting go of the fluid that your body has held onto to process the carbs you were eating. Along with losing this excess fluid, you will also lose some essential electrolytes.  It’s important to supplement magnesium, salt (sodium) and potassium in a way that you don’t have to with other ways of eating – especially at the start. 

If you ate lots of carbs prior to keto, then you can expect that you’ll be more likely to get keto flu (so make sure to follow the advice here!). Whilst you might feel like you could drink a swimming pool in those first few days, drink to thirst but don’t over drink too much as this will flush out more electrolytes. If you ate a lot of carbs before keto, you might find that dropping your carbs back over 2-3 weeks rather than going cold turkey will reduce the chance of keto flu for you if you are struggling with it. 


A massive amount of people in this group choose not to supplement with these other than for keto flu (or at all) and still do successfully – but they will help you get through keto flu at a minimum, and it can help with a number of keto problems, so try it!



Firstly, talk to your doctor regarding this if you have a medical condition such as a heart, kidney or cancer related medical history especially as adding electrolytes or starting keto can impact these. 

If you take anti-depressants, avoid magnesium with 5-HTP in it as this isn’t able to be taken with anti-depressants.

The three you want to supplement are: 


You can add this by getting a good amount of potassium rich foods such as these: 

Another option, particularly in the first couple of weeks, is to use a low-sodium salt such as Mrs Rodgers Low Sodium Salt from the salt section in some supermarkets or potassium chloride supplement from somewhere like HealthPost, iHerb or Health 2000 . Another option is cream of tartar. We don’t find that people need to supplement potassium long term unless they have symptoms such as ongoing cramps and other electrolytes haven’t helped. You don’t want to have too much of this as whilst too little isn’t comfortable, lots can be dangerous. The shot recipe below is a good way to use this. 

This is especially helpful in the early days of keto to avoid of combat keto flu!

Low Sodium Salt

SODIUM aka Salt 
This can be as simple as adding salt to your meals, but in early keto, supplementing (with the recipe below). Remember, keto helps you pee out that retained water, so having extra salt isn’t a problem the way it is when you are non-keto – so salt that food! You can use pink salt, salt flakes, Himalayan salt, etc if you wish, but just make sure to get that salt! 


It’s helpful to take a magnesium supplement – this helps with cramps and lots of other body processes. It doesn’t matter too much which one you use but some (such as magnesium glycinate or citrate) are more gentle on the tummy if you find you are getting an upset tummy after having them. Ideally, you want around 300mg per day.

Generally, we’d suggest supplementing electrolytes by:  

  • Getting medical advice first if you have a medical condition. Then…
  • Increasing high potassium food OR a using potassium supplement for the first few weeks. 
  • Increasing the amount of salt you use long term . Salting your food is ideal, but at the start, you might need to have a shot or two of salted water as well. The recipe for this is below. 
  • Including a magnesium supplement into your daily routine in the mid to long term. 
  • Electrolyte Drinks

Loaded Zero (electrolyte drink from the supermarket in the section with Powerade) is a reasonable quick option when you feel terrible. To get the benefits of this, you really need to have between half and a whole bottle. Loaded zero has around 400mg sodium and potassium. 

Powerade zero has no potassium, so loaded zero is a higher electrolytes option.

Ultima powder from iHerb is one of the few commercial dry keto-friendly options if you want some for on the go: (This is our referral affiliate link)

Quick and Easy Electrolyte Shot

This has similar amounts of electrolytes as a bottle of loaded zero  and is particularly useful early on in keto to avoid or help keto flu. It’s recommended to have this 2x a day with keto flu, but you can reduce it after that. You can make these up in small containers when starting keto pre-prepared for the day or two so you don’t have to make them every time you need one. I generally use 2 of these a day when experiencing keto flu symptoms or in early keto and then stop after a few days to a week. 


All you need is:

1/4 tsp Low Sodium Salt or ½ tsp cream of tartar

1/4 tsp of Salt

There are two ways of taking it. 

ONE: Put it in the bottom of a cup, add a bit of water (about 1-2cm deep) and wait til dissolved. Once dissolve, gulp it down followed with a glass or two of water. Tastes terrible, but gets them in quickly. A couple of drops of stevia (or tiny bit of natvia) in it can help the after taste a lot! Make sure to have this alongside a meal with a glass of water rather than on it’s own. 

TWO: Put them in a litre bottle and add flavouring if wanted – some use tea (peppermint and stevia for instance), water drops or even sugar free drink flavouring such as Thriftee – don’t use a flavouring that has maltodextrin though (as it acts like sugar). 

The electrolyte liquids such as elite won’t be a problem for keto (assuming they don’t contain glucose or dextrose) but they aren’t high in electrolytes either. Berocca has minimal electrolytes needed for keto, so it’s best to use these electrolytes first (but you can find the carb content on the NZ Berocca website if needed). Pharmacy electrolytes predominantly have glucose or some form of sugar/carbs. Vitafresh and sugar-free raro has maltodextrin which acts like a carb.

It’s important to not overdose on potassium especially – The recommended daily intake across all foods for potassium is 2800mg for woman and 3800mg for Men (19+ years old). If you take Panadol/paracetamol or similar for headaches, it’s an option to take that helps for some people. I can’t recommend it as I’m not a doctor, but if you know that medically you can, something you could choose to take. Personally when I’m experiencing keto flu, I tend to take an electrolyte shot and a couple of glasses of water, Panadol and take myself off to bed once I can. I usually feel pretty much better in the morning. 

Overall, if you are eating lots of carbs prior to keto, you might want to look at reducing them slower instead. And make sure to supplement those electrolytes in the early days to stop those headaches and keto flu symptoms!