4 types of medications that can interfere with anesthesia

Patients with cancer may take all kinds of medications – whether they’re used to treat cancer, its side effects, or other conditions that have nothing to do with a cancer diagnosis. 

While medications are a part of daily life for many of us, there are times when you should adjust your dose or even stop taking certain medicines. 

“Before you undergo anesthesia for any reason, you want to be sure you’re not taking any medicines that may cause a problem with anesthesia or your procedure,” says Shannon Popovich, M.D., medical director of MD Anderson’s Perioperative Evaluation and Management Center.

Here, Popovich shares four types of medication to be mindful of before anesthesia. 

1. Blood pressure and heart failure medications

Patients may take these to help treat high blood pressure or heart failure. These drugs include beta-blockers, ACE inhibitors, angiotensin receptor blockers, direct renin inhibitors or diuretics. When a patient is under anesthesia, we monitor their blood pressure very closely, and some of these medications can lower your blood pressure more when combined with anesthesia.

If you’re taking any medication to lower your blood pressure, that can really complicate our efforts to maintain your blood pressure during surgery or any other treatment performed under anesthesia. We generally suggest patients stop taking ACE inhibitors, angiotensin receptor blockers or direct renin inhibitors 24 hours before undergoing anesthesia to reduce the risk of your blood pressure falling too low when combined with anesthesia.

Beta-blockers, calcium channel blockers and medications for heart failure should be taken as usual. They’re not as likely to complicate your blood pressure during anesthesia.

2. Type 2 diabetes medications

Certain drugs used to help regulate blood sugars for patients with diabetes and pre-diabetes should be discussed with your physician before receiving anesthesia. Two specific classes of drugs are particularly concerning: GLP-1 agonists and SGLT-2 inhibitors. Medications called GLP-1 agonists (Semaglutide) before anesthesia can increase the risk of vomiting and aspiration because they slow the time it takes for food to leave your stomach. Even when patients stop eating for the advised period before anesthesia, these drugs may still cause them to have a full stomach.

We generally ask patients to temporarily stop taking these medications based on how often they take them. For example, if you take the drug once a week, stop taking it a week before anesthesia. If you take it once a day, hold it the day of surgery, and consider holding it the day before to reduce your risk of a full stomach.

SGLT-2 inhibitors are known to place patients at risk for euglycemic ketoacidosis when the body is under stress or they are fasting. This is a dangerous condition, and these medications should be held 3 to 4 days before anesthesia, depending on which drug you’re taking. Talk to your prescribing doctor to learn what they recommend for you.

If you’re concerned about how holding your diabetes medication may affect your blood glucose levels, talk to your endocrinologist or prescribing doctor to see what they recommend.

If you take insulin to help manage Type 1 diabetes, continue taking it as you normally do. MD Anderson patients will discuss specific recommendations with the Perioperative Evaluation and Management team or Endocrinology teams before anesthesia.

Insulin taken for Type 2 diabetes may be adjusted in the 24 hours before anesthesia as instructed by your doctor. But be sure to tell your care team about your medication and dosage.

3. Weight loss medications

Although some diabetes medications, like GLP-1 agonists, may help patients with weight loss, there’s another class of drugs solely aimed at weight loss. These are stimulants and work by decreasing appetite and increasing your heart rate. That stimulation can have an unwanted effect when combined with anesthesia.

Drugs that contain phentermine need to be held for 4 days before anesthesia, but when combined with another medication (like topiramate) may need to be slowly tapered off over time. Be sure to talk to your care team about your dose and type of medication so we can wean you off safely.

4. Blood thinners and blood clotting drugs

If you’re undergoing anesthesia before surgery, you might need to stop blood thinning medications – even over-the-counter ones like ibuprofen or Advil – to avoid the risk of excessive bleeding. Talk with your surgeon or proceduralist about any blood thinners you’re taking. For less-invasive procedures like MRI, you should be able to keep taking blood thinners as normal.

Some medications are important to keep taking

Most patients will be able to start taking their regular medications again soon after waking up from anesthesia. In many cases, you may be able to start taking your medications again after you’ve had something to eat and are cleared after surgery.

Although there are several medications to avoid before anesthesia, there are many you can – and should keep taking. Patients who take birth control should continue doing so to avoid the risk of becoming pregnant. This is especially important for patients undergoing chemotherapy or radiation therapy, which can be dangerous to unborn babies.

Antidepressants, anxiety medication and most medicines used to treat ADHD are also safe to continue. If you use sleep aids to help ease insomnia, you can also keep taking them as directed.

The most important thing is to be honest about any drugs you’re taking – prescription or not – so your care team can give you the best advice for your unique needs.

Request an appointment at MD Anderson online or by calling 1-877-632-6789.