Tablet Splitting When Two Halves Don't Equal a Whole

Many medicines come in different strengths. For example, a medicine may come in both a 10 mg and a 20 mg tablet. Surprisingly, the higher dose often costs about the same as the lower dose. If the medicine is too expensive for some people, doctors may prescribe the higher dose and direct them to take half a tablet for each dose. However, splitting tablets may be risky for several reasons.

First, it is easy to become confused about the correct dose. One woman learned this when she was admitted to the hospital with heart and blood pressure problems. Her doctor found that she had been taking the wrong dose of her blood pressure medicine, lisinopril. She was supposed to be taking 5 mg twice a day, but the label on her prescription bottle said there were 10 mg tablets inside.

Initially, the woman had been taking a 20 mg tablet twice a day. When her doctor lowered the dose to 10 mg, she had the new prescription filled. She then cut the leftover 20 mg tablets in half and put them in the same bottle that held the 10 mg tablets. Later, her doctor lowered the dose to 5 mg twice a day. Instead of filling the new prescription for 5 mg tablets, she tried to find all the 10 mg tablets to split them in half, but some remained whole. No one could be certain of the dose the woman had been taking before she was hospitalized.

A study done by the Veterans Administration showed that most people took too much medicine because they forgot to split their tablets. Pharmacists caught these mistakes because people came in too soon to refill their prescriptions. One in 10 people who forgot to split their tablets were harmed by this mistake.¹

The accuracy of split tablets is also questionable. Studies show that the actual dose in each half of a split tablet is often different, so they are not equal. Some halves have more medicine, others have less medicine, even if the tablet is scored (a depressed line in the center of a tablet that helps you split the tablet). Split tablets also crumble more easily, so there may be less medicine in the half tablet by the time you take it. Some tablets are too small or have an unusual shape so they can’t be split evenly. Others are coated with a substance that helps to release the medicine slowly. Splitting these tablets destroys the coating, so you might absorb the medicine too fast.²

Taking whole tablets that equal your exact dose is safest. However, tablet splitting may be necessary if the medicine does not come in the exact dose you need, or if you cannot swallow a tablet whole.

To stay safe if you need to take half tablets, follow these guidelines:

• Ask first. Always check with your pharmacist to be sure it is safe to cut tablets in half. Not all tablets can be split. Some can cause overdoses or unwanted side effects if they are cut or broken.
• Know your limits. Tablet splitting requires sharp eyes and steady hands to do it correctly. Seek help from family members or your pharmacist if you have poor eyesight or any condition that makes it hard to use your fingers and hands, such as arthritis or tremors.
• Get the right tools. Ask your pharmacist for a tablet-splitting device that can help improve the accuracy of each half tablet.
• Keep it clean. Wash and  completely dry your hands before handling any tablets out of the bottle. After using your tablet-splitting device, wash it to remove any leftover powder or particles. Be sure it is clean and dry before using it again.
• Keep them separate. It is never safe to mix different tablets together in prescription bottles, even if they contain the same drug but different doses. You could mistakenly split the wrong tablet or take the wrong medicine. Ask your pharmacist about getting additional medicine containers for your split tablets.

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