Medication is not cheap, so I can understand why people consider splitting their pills. Perhaps your doctor cut your dose in half, and you don’t want to spring for a new prescription when you still have plenty of the previous prescription left. Or maybe the new strength your doctor prescribed costs more than the larger dose that you had been getting (sounds weird, but I’ve seen it happen).

But not all pills and tablets should be split.

As a rule of thumb, special formulations such as extended-release, controlled release formulations should never be split (although there are a few exceptions).

On the other hand, medications for chronic conditions such as blood pressure and diabetes are usually OK to split as long as they don’t have these special coatings. One good example of a medication that should never be split is enterically coated aspirin. “Regular” aspirin can irritate your stomach or aggravate conditions such as ulcers or acid reflux. For this reason, some aspirin is formulated with a special coating that helps the aspirin get past the stomach before it breaks down to help people with these conditions avoid some discomfort. But splitting aspirin with this special coating breaks down the medication’s protective barrier and sets you up for some major stomach pains. Ouch!

Some—but not all—medications that are okay to split come scored, or have grooves, across the pill or tablet’s center. The groove is a “center line” that guides you where to split your medication, so it breaks evenly, and you get the same amount of drug with each new dose.

And for those of you who may be tempted to break pills with a knife, your bare hands, or some other unidentified object, I encourage to you resist the urge and spring for a pill cutter. You can get a decent pill splitter for just a few dollars, and they can save you a lot of headache by guaranteeing you get the same size—and dose—with each cut.

Some pharmacists recommend splitting your pills right before you use them to minimize the amount humidity to which the extra surface area is exposed. While this is definitely a great tip, unfortunately, this is not always the most convenient solution in our increasingly fast-paced world where you may not have the time or forget to split your pill before you head out the door. If you need to cut a few pills in advance, just make sure that you store in them in a cool environment away from light and moisture—just as you would do with your other medications.

Before splitting your medications, double-check with your doctor or pharmacist. The tips above are a general guide, but your doctor or pharmacist can help you find the solution that works best for you.