Medication Information Leaflet

What is this medication for?

Tolbutamide is used to manage diabetes. It helps the pancreas to release more insulin to bring your blood sugar levels down.

How should I take/use this medication?

Take the tablet(s) as directed by your doctor immediately before meal(s). Do not miss or delay  meals after taking the medication.

What should I do if I forget to take/use this medication?

If you miss a dose, take your next dose immediately before your next meal and skip the dose you missed. Do not double your dose or use extra medication to make up for the missed dose.

What precautions should I take?

Inform your doctor if 
  • you are allergic to this medication or any of the other ingredients of this medication
  • you have a genetic condition called Glucose-6 Phosphate Dehydrogenase (G6PD) deficiency
  • you are pregnant, planning to become pregnant, or breastfeeding
  • you have a heart condition, kidney or liver problem
  • you drink alcohol often
  • you are eating less than usual due to sickness/ changed diet as your medication dosage may need to be changed
  • you are exercising more than usual or if you want to change your usual diet, as this may affect your blood sugar level. 
If your doctor has informed you that you need to do a fasting blood test, skip your medication until after you have your blood taken and are ready to eat.

What are some common side-effects of this medication?

This medication may cause low blood sugar (hypoglycemia). Symptoms of low blood sugar are weakness, dizziness, hunger, sweating, trembling, blurred vision, walking unsteadily or fast heartbeat.

If you experience any of these low blood sugar symptoms, do the following immediately: 

Step 1: Check your blood sugar with a home blood sugar meter (glucometer) if available. If your blood sugar level is less than 4 mmol/L, take 15 grams of sugar such as: 
  • 3 glucose tablets or 
  • Half a glass of fruit juice or 
  • 3 teaspoons of sugar, honey or syrup 
Step 2:  You should feel better after 15 minutes. If you have a home blood sugar meter, you should check your blood sugar level again. 

Step 3: If your blood sugar level is still less than 4 mmol/L or you still have symptoms of low blood sugar, you should take another 15 grams of sugar. 

If your symptoms still do not get better, see a doctor or go to the hospital immediately.

You may also gain weight with Tolbutamide. You are encouraged to exercise regularly to prevent weight gain associated with this medication.

What are some rare but serious side-effects that I need to seek medical advice immediately?

See a doctor or go to the hospital immediately if your blood sugar level is always low and experience symptoms even after taking amounts of sugar (see instructions above for management of low blood sugar).

What food or medication should I avoid when I take this medication?

Avoid taking alcohol with this medication as it may cause symptoms such as flushing, nausea, vomiting, headache, fast heartbeat, fast breathing and giddiness.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children.

How should I dispose of this medication safely?

Pack this medicine into a black trash bag and seal it tightly before throwing into the rubbish chute or bin.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore.

Last updated on May 2019

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