What are SGLT-2 inhibitors?
SGLT-2 inhibitors are medicines used to help treat Type 2 Diabetes.
These medicines help lower blood sugar levels by removing excess glucose through the urine.
Examples include:
- Empagliflozin (Jardiance®)
- Canagliflozin (Invokana®)
- Dapagliflozin (Forxiga®)
- Ertugliflozin (Steglatro®)
These medicines are generally very safe and effective. However, there are some rare but serious side effects that patients should be aware of.
Important Rare Side Effects
Diabetic Ketoacidosis (DKA)
Diabetic ketoacidosis is a serious condition where the body produces high levels of acid (ketones) in the blood.
This can occasionally happen even if blood sugar levels are normal.
Symptoms of DKA
Seek urgent medical advice if you develop:
- Nausea or vomiting
- Stomach/abdominal pain
- Fast or deep breathing
- Extreme tiredness or drowsiness
- Fever
- Confusion
- Feeling very unwell unexpectedly
DKA is rare and is estimated to occur in between 1 in 1,000 and 1 in 10,000 patients taking an SGLT-2 inhibitor.
Fournier’s Gangrene
Fournier’s gangrene is a very rare but serious infection affecting the genital or groin area.
It can spread quickly and requires urgent hospital treatment.
Symptoms of Fournier’s Gangrene
Seek urgent medical advice if you develop:
- Severe pain, tenderness, redness, or swelling around the genitals or groin
- Fever
- Feeling generally unwell or unwell very quickly
Although extremely rare, this condition can become life-threatening if not treated promptly.
When Should I Stop My SGLT-2 Inhibitor?
Sick Day Rules
You should temporarily stop taking your SGLT-2 inhibitor if you are unwell, particularly if you have:
- Vomiting or diarrhoea
- Fever
- Significant infection (such as chest infection or urine infection)
- Reduced food intake
- Dehydration
- Severe illness
- Low blood pressure or dizziness
- Been admitted to hospital
- Planned surgery or procedures involving fasting
Surgery or Procedures
Minor procedures or fasting
Stop your SGLT-2 inhibitor on the day of the procedure.
Major surgery
Stop your SGLT-2 inhibitor 24 hours before surgery.
Only restart the medication once you are:
- Eating and drinking normally
- Fully recovered
- No longer dehydrated
- Fully mobile
Other Medicines to Stop During Illness (“Sick Day Rules”)
Some medicines can increase the risk of dehydration or kidney problems during illness.
You may be advised to temporarily stop the following medicines during significant illness causing dehydration:
- ACE inhibitors (medicines ending in “pril”)
- ARBs (medicines ending in “sartan”)
- Diuretics (“water tablets”)
- Metformin
- NSAIDs such as ibuprofen or naproxen
- SGLT-2 inhibitors (“gliflozins”)
Restart these medicines once you have been eating and drinking normally for 24–48 hours.
Do not stop medicines long term unless advised by a healthcare professional.
When to Seek Urgent Medical Advice
Contact your GP practice, NHS 111, or seek urgent medical attention immediately if you develop symptoms of:
- Diabetic ketoacidosis
- Fournier’s gangrene
- Severe dehydration
- Significant breathing difficulties
- Confusion or severe drowsiness
If your GP practice is closed, contact:
Tell the clinician you are taking an SGLT-2 inhibitor and are concerned about possible side effects.
Monitoring While Unwell
If you have diabetes and feel unwell:
- Check your blood glucose levels more frequently if possible
- Drink plenty of fluids
- Try to maintain carbohydrate intake
- Seek medical advice early if symptoms worsen
Some patients may require blood ketone testing or hospital assessment.
Further Information
For more information about sick day rules and medicines affecting the kidneys:
Derbyshire Medicines Management – Medicines and Your Kidneys (PDF)
Please keep this information for future reference.