Yes, half a 20mg tablet is 10mg — but only if you split it correctly

If your tablet has a score line down the middle, half of a 20mg tablet is 10mg. The score line exists so you can break the tablet along that line and get two equal pieces. Without a score line, you cannot assume the active ingredient is evenly distributed, and breaking it may not give you 10mg.

Before you split any tablet, check your prescription label or the information sheet that came with the medication. It will tell you whether the tablet is scored and whether splitting is safe for that particular drug. Some medications should never be cut, even if they have a score line.

Key Takeaways

  • A scored 20mg tablet can be split in half to make two 10mg doses, but only if the score line runs all the way across the tablet.
  • Tablets without a score line should not be split because the medication may not be evenly distributed throughout the tablet.
  • Some medications are unsafe to split even if they are scored, so always check the information sheet or ask your pharmacist before cutting.
  • Use a pill splitter (a small device sold at pharmacies) rather than a knife or your hands, which can cause uneven breaks and waste medication.
  • Store the unused half in a clean, dry container and use it within the timeframe your pharmacist recommends.

When a score line means the tablet is safe to split

A score line is a thin groove pressed into the tablet during manufacturing. It runs from one edge of the tablet to the opposite edge, usually straight down the middle. This groove makes it easier to break the tablet into equal pieces and signals that the manufacturer designed the tablet to be split.

The presence of a score line does not automatically mean you should split the tablet. It means the tablet can be split. Your doctor or pharmacist must confirm that splitting is the right dose for you. If your prescription says to take half a tablet, or if your pharmacist has told you to split it, then a scored 20mg tablet will give you approximately 10mg per half.

Why tablets without a score line should not be split

Unscored tablets are made with the assumption that you will swallow them whole. The active ingredient may be concentrated in one part of the tablet or distributed unevenly throughout. Breaking an unscored tablet in half does not may provide you get 10mg in each piece — you might get 8mg in one half and 12mg in the other.

If your prescription requires a 10mg dose but you have only a 20mg unscored tablet, contact your pharmacist. They can order the correct dose, or in some cases they can tell you whether it is safe to split that particular medication despite the lack of a score line. Never guess.

How to split a tablet safely and evenly

A pill splitter is a small plastic or metal device with a blade and a compartment that holds the tablet steady. You place the tablet in the compartment with the score line aligned with the blade, close the lid, and press down. The blade cuts the tablet cleanly along the score line. Pill splitters cost between two and five dollars and are sold at most pharmacies without a prescription.

Do not use a knife, scissors, or your hands. A knife can slip and cut your finger, and your hands or a knife blade will not explore even pressure across the score line. You may end up with one large piece and one small piece, or tablet dust that you cannot measure. A pill splitter removes the guesswork and waste.

Medications that should never be split, even if scored

Some medications have a score line but should not be split because the drug is formulated as an extended-release or delayed-release tablet. These tablets are designed to release the medication slowly over several hours or to release it in a specific part of your digestive system. Splitting them destroys that design and can cause the entire dose to enter your bloodstream at once, which may be unsafe.

Extended-release tablets often have "XR", "ER", "LA", or "SR" in the name (for extended-release, long-acting, or sustained-release). If you see any of these abbreviations on your label, do not split the tablet even if it has a score line. Ask your pharmacist whether a lower dose is available as a separate tablet.

How to store the unused half

After you split the tablet, store the unused half in a clean, dry container — not the original bottle if it is a large bottle meant for whole tablets. A small pill bottle, a sealed plastic bag, or a small glass jar works well. Keep it in the same cool, dry place where you store the rest of your medications, away from light, heat, and moisture.

Ask your pharmacist how long the split tablet will remain safe to use. Most split tablets are good for a few weeks to a few months, depending on the medication and storage conditions. If you are unsure whether the unused half is still safe, do not take it — throw it away and use a fresh tablet from the bottle.

What to do if your tablet is not scored

Contact your pharmacy and explain that you need a 10mg dose. Your pharmacist can order 10mg tablets if they are available, or they can tell you whether it is safe to split the 20mg tablet you have. In some cases, a medication is available in multiple strengths, and switching to the lower dose is simpler and safer than splitting.

If 10mg tablets are not available and splitting is unsafe, your pharmacist may recommend a different medication that comes in the dose you need, or they may have other options. Do not attempt to split an unscored tablet on your own.

Frequently Asked Questions

Can I split a tablet with a score line using a knife?

You can, but a pill splitter is safer and more accurate. A knife can slip, cut your finger, or explore uneven pressure that creates one large piece and one small piece. A pill splitter costs a few dollars and takes the guesswork out of splitting.

What if I split the tablet and one half is noticeably larger than the other?

If the pieces are visibly unequal, do not use either one. Throw both halves away and use a fresh tablet from the bottle. An unequal split means you cannot be sure of the dose you are getting.

Can I split a tablet and save the other half for later?

Yes, if your pharmacist confirms it is safe to split and store. Keep the unused half in a clean, dry container and ask your pharmacist how long it will remain safe. Most split tablets last a few weeks to a few months depending on the medication.

What if my prescription says to take one tablet but I only need 10mg?

Contact your doctor or pharmacist. They may need to adjust your prescription to reflect the correct dose, or they may have ordered the wrong strength by mistake. Do not split a tablet unless your doctor or pharmacist has told you to do so.

Are there medications that look scored but should not be split?

Yes. Extended-release and delayed-release tablets often have a score line but should never be split. Check your medication label for "XR", "ER", "LA", or "SR". If you see any of these, ask your pharmacist before splitting, even if a score line is visible.