Splitting pills is controversial, but more and more doctors and even some insurance companies are advising patients to go ahead and do it to save money on prescription drugs.

But not all drugs can be safely split.

So how much can you really save and stay safe at the same time?

If you take 20 milligrams of the cholesterol drug Lipitor daily, a 30 day supply can cost around $125. But a 30-day supply of 40 milligram Lipitor tablets is the same price. If you buy the 40 milligram tablets--split them in half--you get a two month supply for the price of one.

But is it safe?

A study by the University of Michigan found splitting cholesterol pills did not negatively effect cholesterol levels and a Duquesne University pharmacy professor agrees.

"As long as you follow rules and that you do it correctly. There are many medications that cannot be split," said Professor Monica Skoma.

Joe Bettinger, owner of Heibers pharmacy in Oakland, showed us how hard it is to get an even split.

He cut a pill in half and weighed it.

"So there is a 20 percent swing," said Heibers.

That can make a big difference.

"They are going to get too much medicine which means blood pressure will get too low. Symptoms like dizziness may happen. Or if it's not high enough, the medication could cause people's blood pressure to be a little higher than it should be," said Bettinger.

So if you want to split pills to save money, always check with your doctor and your pharmacist first. Medicines like blood thinners, anti-seizure medicines and pain pills should not be split

"Oxycontin is a big one. Never split that one cause it will cause a toxic overdose," said Bettinger.

Also on the no-split list are coated, time-released drugs with any sort of special delivery system. Splitting them may destroy the integrity of the medication.

Doctors tell us if you do decide to split, always use a pill splitter and don't split all your pills at once because moisture and light can eventually break down the medication.