Sauna on metformin, Jardiance or Farxiga: dehydration is the risk to plan for
None of these labels mentions saunas. The metformin leaflet does name sweating a lot without drinking enough as a way to get dehydrated, and the Jardiance and Farxiga guides spell out what dehydration does on their drugs. That is the whole sauna question.
Short answer: None of these labels forbids a sauna. The metformin patient leaflet lists getting dehydrated among the things that raise the risk of lactic acidosis, and says dehydration can happen when you sweat a lot and do not drink enough fluids. The Jardiance and Farxiga guides say their drugs can dehydrate some people, which can cause dizziness, fainting or weakness, especially on standing. So drink before and after, eat first, keep sessions short, stand up slowly, and skip the sauna when you are ill or not drinking normally.
A sauna on metformin, Jardiance (empagliflozin) or Farxiga (dapagliflozin) is not something any of the labels forbids, and we found no study that tested the combination. What the labels share is a concern about dehydration, and a sauna is, among other things, a way to lose water quickly.
The metformin patient leaflet is unusually direct about it. Among the situations that raise the risk of lactic acidosis, it lists getting dehydrated, and says this can happen with fever, vomiting or diarrhea, and also when you sweat a lot with activity or exercise and do not drink enough fluids.
This is general information, not medical advice, and it gives no dosing advice. Whether and when to take any of these medicines, including around illness, belongs to your prescriber.
What the metformin label says about dehydration
The label’s boxed warning is about lactic acidosis, a rare but serious build-up of acid in the blood. It lists the risk factors: kidney problems, certain drugs such as topiramate, age 65 or older, imaging with contrast dye, surgery and other procedures, hypoxic states such as acute heart failure, excessive alcohol intake and liver problems.
The patient leaflet adds dehydration to that picture in plain words, including the sweating example above. MedlinePlus asks you to tell your doctor if you have had severe diarrhea, vomiting or fever, or if you drink much less fluid than usual for any reason, because your doctor may pause metformin until you recover. That decision belongs to them, not to you.
The label also lists increased sweating among its less common side effects, reported in 1% to 5% of people in trials.
Low blood sugar: why eating first matters
Metformin rarely causes low blood sugar on its own, the leaflet says. But it adds that hypoglycemia can happen if you do not eat enough, if you drink alcohol, or if you take other medicines to lower blood sugar.
That combination is exactly what a spa day can produce: a skipped lunch, a glass of wine, and heat. Our diabetes guide covers what heat can do to blood sugar, especially on insulin or a sulfonylurea, and our guide to eating before a sauna or cold plunge covers the timing.
What the Jardiance and Farxiga labels say about dehydration
Jardiance and Farxiga work by making the kidneys pass sugar into the urine, and the labels treat fluid as part of the deal.
The Jardiance medication guide says the drug can cause some people to become dehydrated, meaning the loss of body water and salt, and that dehydration may cause you to feel dizzy, faint, light-headed or weak, especially when you stand up. It says you may be at higher risk if you take medicines to lower your blood pressure, including water pills, are on a low-salt diet, have kidney problems, or are 65 or older, and it asks you to talk to your healthcare provider about how much fluid to drink each day. The Farxiga guide gives the same list.
The prescribing information for both tells doctors to inform patients that dehydration may increase the risk of low blood pressure and that they should keep up an adequate fluid intake.
Note that these drugs are not only for diabetes. The Farxiga label includes chronic kidney disease and heart failure among its uses, and the Jardiance label includes heart failure. The dehydration warning applies whatever you take it for.
Ketoacidosis: the warning sign to know
Both guides also warn about ketoacidosis, a serious build-up of ketones. The Jardiance guide says it has happened in people with type 1 or type 2 diabetes, including people who were sick, and that it can happen even if your blood sugar is below 250 milligrams per deciliter.
It lists the symptoms: nausea, vomiting, stomach-area pain, tiredness and trouble breathing, and it tells you to call your healthcare provider or go to the nearest emergency room right away if you get them. Some of those can be mistaken for feeling rough after too much heat. If you feel that way after a sauna and it does not settle quickly with cooling down and water, treat it as the label says, not as a heat hangover.
A sauna plan on metformin, Jardiance or Farxiga
Build it around fluid, food and standing up.
Before. Drink water in the hour before, eat a normal meal a couple of hours ahead, and skip the sauna on days you are ill, vomiting, have diarrhea or a fever, or are not drinking normally.
During. Keep rounds short and sit on a lower bench, where it is cooler. Leave at the first sign of dizziness or feeling unwell.
Standing up. Sit for a minute before you stand, then stand in two stages and hold a rail. The Jardiance and Farxiga guides single out dizziness on standing, and our guide to what to do if you feel faint in a sauna covers the moment itself.
After. Drink water, eat if it is time to, and go easy on alcohol, which the metformin label names as a risk factor in its own right. Our guide to alcohol and the sauna covers why the two combine badly.
Metformin, Jardiance, Farxiga and heat at a glance
| Practice | Fine as is | Needs adjusting | Avoid |
|---|---|---|---|
| Sauna | Short rounds with water and food | Lower bench, slow exit | Sessions when ill or not drinking normally |
| Hot tub, hot bath | A soak you are used to | Climb out slowly | Long soaks after alcohol |
| Hot yoga, heat training | Classes you are used to | Extra water before and after | Hard sessions on an empty stomach |
| Cold plunge | Brief dips | Nothing specific in the labels | Nothing specific in the labels |
| Alcohol at the spa | Nothing specific | Very little, with food | Drinks before or between heat rounds |
| Older age, blood pressure pills, kidney problems | Nothing without advice | Ask how much to drink daily | Heat without a fluid plan |
What is oversold about saunas and blood sugar
The popular claim is that a sauna or hot tub treats insulin resistance. There is a small, much-quoted hot tub study, and our diabetes guide weighs it, but none of it is a reason to change a treatment plan, and none of it tested these drugs.
The second claim is that sweating is a way to flush sugar or toxins. The only thing a sauna reliably removes is water and salt, which is exactly what these labels ask you to keep up.
What belongs to your prescriber
Whether heat suits you, how much you should drink each day, and what to do with your medicine when you are ill all belong to your prescriber. Ask specifically if you are over 65, take blood pressure pills or water pills, have kidney problems, or also take insulin or a sulfonylurea.
If you also use a glucose sensor or a pump, our guide to CGMs and insulin pumps in the sauna or hot tub covers the devices, and our Ozempic, Wegovy and Mounjaro guide covers the injectable drugs. The guide to heat, cold and common medications and the one-page medication and heat checklist cover the rest.
Our medication heat-warning label index quotes what the FDA labels for metformin, Jardiance and Farxiga say about heat, sweating, dehydration and the sun, word for word, with a link to each label.
FAQ: saunas and hot tubs on metformin, Jardiance or Farxiga
Can I use a sauna on metformin? The metformin label does not forbid it. Its patient leaflet lists getting dehydrated, including by sweating a lot without drinking enough, among the things that raise the risk of lactic acidosis. Drink water before and after, eat first, keep sessions short, and skip the sauna when you are ill or not drinking normally.
Is a sauna safe on Jardiance or Farxiga? The labels do not mention saunas, but both guides say the drug can cause dehydration, which can make you dizzy, faint or weak, especially when you stand up. Keep sessions short, drink water, stand up slowly, and ask your prescriber how much fluid you should drink each day.
Can metformin make you sweat more? The metformin label lists increased sweating among its less common side effects, reported in 1% to 5% of people in clinical trials. Heavy sweating in a sauna adds to fluid loss, so drink to replace it.
Can I have a hot tub and a glass of wine on metformin? The metformin label names excessive alcohol as a risk factor for lactic acidosis and says alcohol can contribute to low blood sugar. A long soak after drinking combines heat, fluid loss and alcohol, so keep alcohol very light, have it with food, and ask your prescriber what is sensible for you.
The bottom line on saunas, metformin, Jardiance and Farxiga
The labels do not warn against saunas. They warn about dehydration, and a sauna is dehydration on a timer. Metformin’s leaflet names heavy sweating without enough fluid, and the Jardiance and Farxiga guides describe the dizziness and fainting dehydration can bring.
So drink, eat, keep it short, stand up slowly, and stay out of the heat on sick days. Treat nausea, vomiting, stomach pain or trouble breathing that does not settle as the labels do: a reason for urgent medical help.