Atenolol and Tolazamide: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 15, 2026 · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Tolazamide
Atenolol
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
Tolazamide (Tolinase) is a pill that lowers your blood sugar, and atenolol (Tenormin) is a beta-blocker for your heart or blood pressure. When you take them together, two things can happen. First, your blood sugar can swing either lower or higher than usual. Second, and this is the important part, atenolol can hide one of the classic warning signs of low blood sugar: a fast or pounding heartbeat.
The good news is that other warning signs, like sweating and feeling shaky or dizzy, usually still show up. The best thing you can do is check your blood sugar a bit more often so you catch changes early. Your care team can easily manage this by watching your numbers and adjusting your dose if needed.
Effect: Beta-blockade with atenolol may alter glycemic control (hypo- or hyperglycemia) and, more notably, blunt the adrenergic warning signs of hypoglycemia, particularly tachycardia. Diaphoresis and dizziness are generally preserved. Neither drug is a prodrug; the interaction is pharmacodynamic, not a CYP-mediated PK effect.
- Direction: variable glycemic effect; masked hypoglycemia awareness
- Onset: delayed
- Evidence: probable
- Note: atenolol is beta-1 selective, so risk is lower than with nonselective agents, but caution still applies
Management: Increase frequency of glucose monitoring. Individualize/adjust the sulfonylurea dose as needed. If atenolol is discontinued, watch for loss of glycemic control.
What happens
Hypoglycemia or hyperglycemia; decreased symptoms of hypoglycemia
Interaction Deep Dive
When antidiabetic medications are taken together with beta-blockers, the result may be either hypoglycemia or hyperglycemia, and the beta-blockers may also mask hypoglycemic symptoms23. While tachycardia may be influenced, other hypoglycemic manifestations such as dizziness and sweating are not 1. Insulin-induced hypoglycemia can be intensified by nonselective beta-blockers, which can also hinder the return of serum glucose to normal levels. In individuals with both heart failure and diabetes, hyperglycemia may worsen 7. It may become necessary to monitor glucose more often or to adjust the dose of the antidiabetic agent 23. During combined therapy, watch carefully for signs and symptoms of hypoglycemia, and should the beta-blocker be discontinued, remain alert for a loss of glycemic control 4.
Why it happens (mechanism)
Altered glucose metabolism and beta blockade
How to manage this interaction
Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. This combination is commonly used and can be managed safely.
- Check your blood sugar more often, especially when you first combine them, so any highs or lows are caught early.
- Learn the signs of low blood sugar that atenolol does NOT hide, like sweating, shakiness, hunger, and confusion, since a racing heartbeat may be blunted.
- Your tolazamide dose may be adjusted and individualized by your care team based on your readings.
- If your atenolol is ever stopped, tell your team, since your blood sugar control may change.
Bring your glucose logs to your pharmacist or doctor to review.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) In elderly diabetic patients receiving either insulin or sulfonylureas, the selection of antihypertensive agent had little impact on the risk of hypoglycemia; however, after adjusting for other risk factors, the lowest risk was observed with cardioselective beta blockers and the highest with non-cardioselective beta blockers, while other antihypertensive agents produced intermediate results (N=13,559) 5.
b) In patients with hypertension and non-insulin dependent diabetes, beta blockers, but not alpha blockade and ACE inhibitors, produced a worsening of long-term glycemic control. Beta blockade was also associated with some adverse effects on the lipid profile. These effects were particularly evident with propranolol. Using an alpha blocker together with the beta blocker prevented the worsening caused by beta blockade 6.
Common questions
Can I take Atenolol and Tolazamide together?
Atenolol can hide a fast heartbeat as a warning sign of low blood sugar and may shift your glucose control, so check your blood sugar more often and know the other warning signs. Your care team can manage this by monitoring and adjusting your tolazamide dose if needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Atenolol and Tolazamide interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How is the Atenolol and Tolazamide interaction managed?
Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. This combination is commonly used and can be managed safely. Check your blood sugar more often, especially when you first combine them, so any highs or lows are caught early. Learn the signs of low blood sugar that atenolol does NOT hide, like sweating, shakiness, hunger, and confusion, since a racing hear… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Atenolol or Tolazamide need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (7)
- Product Information: TENORMIN(R) oral tablets, atenolol oral tablets. AstraZeneca Pharmaceuticals LP (per FDA), Wilmington, DE, 2012. DailyMed
- Product Information: TOUJEO(R) subcutaneous injection, insulin glargine subcutaneous injection. sanofi-aventis (per manufacturer), Bridgewater, NJ, 2015. DailyMed
- Product Information: AMARYL(R) oral tablets, glimepiride oral tablets. Sanofi-Aventis U.S. LLC (per FDA), Bridgewater, NJ, 2013. DailyMed
- Product Information: Glynase(R) PresTab(R) oral micronized tablets, glyburide oral micronized tablets. Pharmacia & Upjohn Co (per FDA), New York, NY, 2013. DailyMed
- Shorr RI, Ray WA, Daugherty JR, et al: Antihypertensives and the risk of serious hypoglycemia in older persons using insulin or sulfonylureas. JAMA 1997; 278:40-43. DOI
- Whitcroft IA, Thomas JM, Rawsthorne A, et al: Effects of alpha and beta adrenoceptor blocking drugs and ACE inhibitors on long term glucose and lipid control in hypertensive non-insulin dependent diabetics. Horm Metab Res Suppl 1990; 22:42-46.
- Product Information: COREG CR(R) extended-release oral capsules, carvedilol phosphate extended-release oral capsules. GlaxoSmithKline, Research Triangle Park, NC, 2011. DailyMed
Keep reading about Tolazamide
Keep reading about Atenolol
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