Acarbose

Pronunciation: pronunciation varies by local usage.

Generic name: acarbose
Brand names: Precose (US), Acarbose Tablets (UK/EU generic)
Drug class: Alpha-glucosidase inhibitor
Form: Tablet
Route: Oral

Availability and supply rules vary by country

Trade names by country: Canada

What acarbose is and how it works

Acarbose is an oral alpha-glucosidase inhibitor that delays the digestion and absorption of starch, dextrin, and disaccharides in the small intestine, thereby reducing postprandial blood glucose rises. (1) (2)

It is used to improve glycemic control in adults with type 2 diabetes mellitus. UK guidance describes use when diabetes is inadequately controlled on diet alone, or on diet plus metformin and/or a sulfonylurea. It does not itself cause hypoglycemia when used alone, but can enhance the glucose-lowering effect of sulfonylureas or insulin. Effectiveness depends on taking it with meals.

Mechanism of action: how acarbose works

Acarbose is a competitive inhibitor of intestinal alpha-glucosidases, delaying the digestion of starch and sucrose into absorbable monosaccharides, thereby reducing postprandial hyperglycemia and smoothing daily glucose fluctuations. (1) (2)

What acarbose is used for

Type 2 diabetes mellitus

Acarbose is indicated for the treatment of type 2 diabetes mellitus to improve glycemic control, either as monotherapy when diet alone is insufficient, or in combination with metformin and/or a sulfonylurea. The exact place in therapy and starting dose may differ by region. (1) (2)

Before taking acarbose

Do not take / not appropriate for

US label: acarbose is contraindicated in patients with known hypersensitivity to acarbose. (US label) (1)
US label: acarbose is contraindicated in diabetic ketoacidosis. Tell your prescriber if this applies to you. (US label) (1)
US label: acarbose is contraindicated in cirrhosis (severe liver disease). Tell your prescriber about any liver disease history. (US label) (1)
Both US and UK/EU labels contraindicate acarbose in inflammatory bowel disease, colonic ulceration, partial intestinal obstruction, or any predisposition to intestinal obstruction. Tell your prescriber if any of these apply to you. (US label and UK/EU SmPC) (1) (2)
Both US and UK/EU labels contraindicate acarbose in chronic intestinal disorders associated with marked disturbances of digestion or absorption. Tell your prescriber if this applies to you. (US label and UK/EU SmPC) (1) (2)
US label: acarbose is contraindicated in conditions that may deteriorate as a result of increased gas formation in the intestine. Tell your prescriber if this applies to you. (US label) (1)
UK/EU SmPC: acarbose is contraindicated in pregnancy and breastfeeding. US label: pregnancy data are insufficient; use only when clearly needed. Tell your prescriber if you are pregnant, may become pregnant, or are breastfeeding. (UK/EU SmPC (contraindication); US label (insufficient-data caution)) (2) (1)
UK/EU SmPC: acarbose is contraindicated in hepatic impairment. Tell your prescriber about any liver problems. (UK/EU SmPC) (2)
UK/EU SmPC: acarbose is contraindicated if kidney function is severely reduced (creatinine clearance below 25 mL/min/1.73m²). Tell your prescriber about any kidney problems. (UK/EU SmPC) (2)

Tell your clinician about

Any history of liver problems, especially cirrhosis or abnormal liver enzymes.
Current bowel conditions such as inflammatory bowel disease, ulceration, or partial obstructions.
Kidney problems and recent kidney function test results.
Pregnancy or plans to become pregnant, or if you are breastfeeding.
All other medicines you are taking, especially insulin, sulfonylureas, metformin, digestive enzyme preparations, activated charcoal, or colestyramine.
If you develop severe or persistent diarrhea, abdominal pain, or bloating after starting treatment.

(1) (2)

How to take acarbose

US label: take acarbose with the first bite of each main meal, three times daily. UK/EU SmPC: swallow the tablet whole with a little liquid directly before the meal, or chew it with the first mouthful of food, three times daily.
The dose is individualized based on 1-hour postprandial glucose, glycosylated hemoglobin (HbA1c), and tolerance.
Tablets should be swallowed whole with a little liquid, or chewed with the first mouthful of food.
Take acarbose exactly as prescribed by your doctor. If you have any questions about your dose or treatment plan, contact your prescriber.
If acarbose is combined with insulin or sulfonylureas, those doses may need adjustment under medical supervision.

(1) (2)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2)

Missed dose

Contact your prescriber or pharmacist for advice if you miss a dose.

Overdose

If you think you have taken more acarbose than prescribed, contact your prescriber, pharmacist, or emergency services promptly for advice. Unlike sulfonylureas or insulin, an acarbose overdose alone will not cause hypoglycemia, but it may cause temporary flatulence, diarrhea, and abdominal discomfort. Per the UK SmPC, eating carbohydrate-containing food or drink around the time of an overdose may make these symptoms more intense, and the advice given may include avoiding carbohydrate-containing food or drink for around 4-6 hours — follow the specific guidance given by whoever you contact. (1) (2)

Side effects

The most common side effects are gastrointestinal, related to how acarbose works in the intestine. The UK SmPC notes that a more gradual initial dose titration may help minimize these effects. Liver enzyme elevations have also been observed on routine testing.

Flatulence (gas)

What to notice: Excessive intestinal gas, bloating.

What to do: This is the most common effect (up to 74% in US trials). It may improve over time or with dietary adjustments. Discuss with your clinician if it becomes bothersome or unmanageable. (1) (2)

Diarrhea

What to notice: Loose or frequent bowel movements.

What to do: Diarrhea occurred in 31% of acarbose users in US trials. If severe, persistent, or leads to dehydration, contact your prescriber. (1)

Abdominal pain

What to notice: Stomach cramps, discomfort, or pain.

What to do: Abdominal pain was reported in 19% of users in US trials. Contact your prescriber if it is severe or persistent. (1)

Nausea and vomiting

What to notice: Feeling sick or being sick.

What to do: These are less common but may occur. If persistent or severe, discuss with your clinician. (2)

Liver injury

What to notice: Elevated liver enzymes (transaminases) may occur; this is usually detected by routine blood testing. Transaminase elevations occurred in 14% of acarbose-treated patients versus 7% of placebo patients in US trials. The specific patient-facing symptom list for liver injury was not established in the sources reviewed for this page.

What to do: Attend your scheduled liver function tests. Contact your prescriber if you have any concerns; they will review your results and decide on any changes to treatment. (1) (2)

Serious warnings

Hypoglycemia when combined with other diabetes medicines — emergency

Symptoms: Acarbose alone does not cause hypoglycemia. When taken with insulin or sulfonylureas (and, per the UK SmPC, also metformin), it may increase the risk of hypoglycemia. The specific symptom list for hypoglycemia was not established in the sources reviewed for this page.

Action: If hypoglycemia occurs, use oral glucose (dextrose) tablets, not sucrose (table sugar), because acarbose delays the breakdown of sucrose. Carry a source of glucose as advised by your care team, and contact your prescriber or seek emergency care if you are concerned. (1) (2)

Liver dysfunction — urgent

Symptoms: Elevated liver enzymes (transaminases) may occur; this is usually detected by routine blood testing rather than by symptoms. The specific symptom list for liver injury was not established in the sources reviewed for this page.

Action: Attend your scheduled liver function tests. Contact your prescriber promptly if you notice anything you're concerned about; they will review your test results and decide on any changes to treatment. (1) (2)

Interactions

Medicine or test	Effect	Action
Insulin, sulfonylureas, metformin	Acarbose can enhance the blood-glucose-lowering effect of these medicines, increasing the risk of hypoglycemia. Dosage adjustments of these agents may be required.	Your prescriber will review your other diabetes medicines and adjust doses as needed. Carry glucose (dextrose) for emergencies. (1) (2)
Activated charcoal and digestive enzyme preparations (e.g., amylase, pancreatin)	These may reduce the effectiveness of acarbose.	Tell your prescriber or pharmacist if you are taking, or plan to take, activated charcoal or digestive enzyme preparations together with acarbose. They will advise whether this combination is appropriate for you. (2)
Colestyramine	The UK SmPC states that concurrent use of colestyramine with acarbose should be avoided, as it may reduce acarbose's effect.	Tell your prescriber or pharmacist if you are taking, or are prescribed, colestyramine. The UK SmPC advises against combining it with acarbose; your prescriber or pharmacist can advise on managing this or suggest an alternative approach. (2)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy and breastfeeding

The UK SmPC contraindicates use during pregnancy and breastfeeding. The US label states there are insufficient data and advises use only when clearly needed. Discuss risks and benefits with your clinician. (1) (2)

Hepatic impairment

Acarbose is contraindicated in cirrhosis (US label) and in hepatic impairment (UK SmPC). Liver function monitoring is recommended. (1) (2)

Renal impairment

The UK SmPC contraindicates acarbose if creatinine clearance is below 25 mL/min/1.73m². (2)

Children

Not established from the sources reviewed: the sources reviewed for this page describe adult type 2 diabetes indications only; no specific pediatric dosing or safety data were found. (1) (2)

Monitoring

Before starting

The following are general clinical considerations your prescriber may take into account, not specific label requirements.
Your prescriber may check kidney function, since the UK SmPC contraindicates acarbose at creatinine clearance below 25 mL/min/1.73m².
Your prescriber may ask about bowel health and any history of inflammatory or obstructive conditions, given the contraindications listed above.
Your prescriber will review your other diabetes medicines and consider whether doses may need adjustment.

During treatment

Monitor blood glucose, especially 1-hour postprandial levels; your prescriber will use these results, along with your HbA1c and tolerance, to decide whether your dose needs to be adjusted.
Check glycosylated hemoglobin (HbA1c) periodically.
Perform liver function tests every 3 months during the first year of treatment (US label) or during the first 6–12 months (UK SmPC).
Watch for gastrointestinal symptoms and their impact on adherence.

(1) (2)

Storage

Follow the instructions on the pharmacy label and package insert, or ask your pharmacist.

Professional information

Clinician-facing context only. Use the current local indication, dosing table, and monitoring recommendations.

United States (FDA label)

Indication: Type 2 diabetes mellitus

Dose summary: Start 25 mg orally three times daily with the first bite of each main meal. Titrate at 4–8 week intervals based on 1-hour postprandial glucose or HbA1c and tolerance. Maximum: 100 mg three times daily if weight >60 kg; 50 mg three times daily if ≤60 kg. (1)

United Kingdom/EU (SmPC)

Indication: Type 2 diabetes mellitus

Dose summary: Start 50 mg three times daily. For gastrointestinal tolerance, consider gradual initiation (50 mg once or twice daily increasing to TID). After 6–8 weeks, dose may be increased to 100 mg three times daily if needed. Maximum: 200 mg three times daily.

Renal context: Contraindicated if creatinine clearance <25 mL/min/1.73m². No dose adjustment table for milder impairment. (2)

Mechanism of action

Hepatic guidance

Contraindicated in cirrhosis (US label) and hepatic impairment (UK SmPC). Monitor liver enzymes routinely (every 3 months during the first year per US label; first 6-12 months per UK SmPC).

Overdose note

Overdose alone does not cause hypoglycemia. It may cause transient GI symptoms (flatulence, diarrhea, abdominal discomfort). UK SmPC notes that carbohydrate intake around the time of overdose may intensify GI symptoms. No specific antidote or other overdose intervention was found in the sources reviewed for this page. (1) (2)

Frequently asked questions

Will acarbose cause low blood sugar if I take it by itself?

No, acarbose alone does not cause hypoglycemia. However, if you also take insulin or sulfonylureas, your risk of hypoglycemia may increase. Always carry glucose (dextrose) tablets, not table sugar, to treat low blood sugar. (1) (2)

Why must I take acarbose with the first bite of a meal?

Acarbose works by delaying the digestion of carbohydrates in your meal, and its effectiveness depends on taking it with meals as directed on the product label (US: with the first bite of each main meal; UK/EU: swallowed whole just before the meal or chewed with the first mouthful). (1) (2)

I have gas and bloating from acarbose. Will it go away?

Flatulence and bloating are common, especially early in treatment. The UK SmPC notes that starting with a more gradual dose increase may help minimize gastrointestinal effects. Talk to your doctor if they persist or are severe or bothersome. (1) (2)

What is the mechanism of action of acarbose?

What is the generic name of Acarbose?

The generic name is acarbose. It is sold under brand names including Precose (US), Acarbose Tablets (UK/EU generic). (1) (2)

What class of drug is acarbose?

Acarbose is classed as: Alpha-glucosidase inhibitor. (1) (2)

References

PRECOSE (acarbose) tablet — prescribing informationU.S. Food and Drug Administration · United States · accessed 2026-08-05 · source 1
Acarbose 100 mg Tablets — Summary of Product CharacteristicsMedicines and Healthcare products Regulatory Agency (MHRA) via electronic Medicines Compendium · United Kingdom · accessed 2026-08-05 · source 2
ACARBOSE TABLET [BRYANT RANCH PREPACK] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
Acarbose — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 4
Acarbose — FDA approval record (Drugs@FDA ANDA202271)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 5
acarbose — RxNorm normalized drug concept (RXCUI 16681)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 6

Brand names by country

Single-ingredient acarbose names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

Canada

GLUCOBAY

View brands in additional countries.