Chlorpropamide and Atenolol: 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
Chlorpropamide
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.
Chlorpropamide is a diabetes pill that lowers your blood sugar, and atenolol is a beta-blocker often used for blood pressure or the heart. When you take them together, two things can happen. First, your blood sugar can move up or down, so it needs a closer eye. Second, and this is the big one, atenolol can hide some of the usual warning signs of low blood sugar, like a fast or pounding heartbeat. You may still feel sweaty, but that racing-heart clue can be muffled.
The good news: your care team can manage this easily by checking your sugar a bit more often and adjusting doses if needed. Keep taking both as prescribed and let them know how you feel.
Interaction: Combined chlorpropamide (sulfonylurea) and atenolol (beta-blocker) can alter glycemic control (hypo- or hyperglycemia) and blunt adrenergic warning signs of hypoglycemia. Neither is a prodrug in a way that changes direction here.
- Mechanism: Beta blockade masks sympathetic symptoms (notably tachycardia) and can impair glucose recovery; altered glucose metabolism.
- Onset: Delayed. Evidence: Probable. Severity: Moderate.
- Note: Atenolol is beta-1 selective, so masking may be less pronounced than with nonselective agents, but the effect can still occur.
- Management: Increase frequency of glucose monitoring; individualize antidiabetic dosing. 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 can be either hypoglycemia or hyperglycemia, and the combination may mask signs of hypoglycemia23. Tachycardia can be affected, though other hypoglycemic manifestations such as dizziness and sweating are not 1. Insulin-induced hypoglycemia can be intensified by nonselective beta-blockers, which may also impede the return of serum glucose to normal levels. In individuals who have both heart failure and diabetes, hyperglycemia may worsen 7. It may become necessary to monitor glucose more often or to modify the dose of the antidiabetic drug 23. During combined use, watch carefully for signs and symptoms of hypoglycemia, and should the beta-blocker be discontinued, monitor 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 as prescribed unless your prescriber tells you otherwise. This combination is manageable with a few simple steps.
- Your team may check your blood sugar more often to catch highs or lows early.
- Your chlorpropamide dose may need to be adjusted and individualized by your care team.
- Know that a racing heartbeat, one usual sign of low blood sugar, may be muffled by atenolol, so watch for other clues like sweating, shakiness, or confusion.
- Tell your team before starting or stopping the atenolol, since that can change your blood sugar control.
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 specific antihypertensive agent selected had little influence on the risk of hypoglycemia; however, once other risk factors were accounted for, the lowest risk was seen with cardioselective beta blockers and the highest with non-cardioselective beta blockers, while other antihypertensive agents fell somewhere in between (N=13,559) 5.
b) In patients with hypertension and non-insulin dependent diabetes, beta blockers, though not alpha blockade or ACE inhibitors, produced a worsening of long-term glycemic control. Certain unfavorable effects on the lipid profile also arose with beta blockade. These effects were particularly evident with propranolol. Using an alpha blocker together with the beta blocker prevented the worsening attributable to beta blockade 6.
Common questions
Can I take Chlorpropamide and Atenolol together?
Taking chlorpropamide with atenolol can shift your blood sugar and hide the fast-heartbeat warning of a low, so monitor more closely and let your care team adjust doses. Watch for sweating and shakiness even if your heart does not race. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Chlorpropamide and Atenolol 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 Chlorpropamide and Atenolol interaction managed?
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. This combination is manageable with a few simple steps. Your team may check your blood sugar more often to catch highs or lows early. Your chlorpropamide dose may need to be adjusted and individualized by your care team. Know that a racing heartbeat, one usual sign of low blood sugar, may be muffled by atenolol, s… 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 Chlorpropamide or Atenolol 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 Chlorpropamide
Keep reading about Atenolol
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