If you're interested in a particular product or service, trying before you buy might seem like a no-brainer. But what starts as a free trial — or for a very low cost — might end up costing you real money. The Federal Trade Commission, the nation's consumer protection agency, wants you to know that some companies use free trials to sign you up for more products — sometimes lots of products — which can cost you lots of money as they bill you every month until you cancel.

Whiter Teeth? Flatter Stomach? Shinier Hair?

Whether it's for a teeth whitener, vitamin or kitchen gadget, all free trials eventually end. And typically, if you don't want to buy what you've tried, you need to cancel or take some other action before the trial is up. If you don't, you may be agreeing to buy more products. But some dishonest businesses make it tough to cancel, hiding the terms and conditions of their offers in teensy type, using pre-checked sign-up boxes as the default setting online, and putting conditions on returns and cancellations that are so strict it could be next to impossible to stop the deliveries and the billing. Or, the "free trial" might come with a small shipping and handling fee. You think you're only paying a couple of dollars, but you're really giving over your credit card information, resulting in much higher charges after the trial.

Strings Attached

Other "free" offers enroll you in clubs or subscriptions. For example, a company might offer you an introductory package of free books, CDs, magazines or movies. If you sign up, you may be agreeing to enroll in a club that will send you more products and bill you until you cancel, or to a subscription that's automatically renewed each year.

Here's What to Do

So how can you avoid the costs that might be hiding in free trials?

• Research the company online. See what other people are saying about the company's free trials — and its service. Complaints from other customers can tip you off to "catches" that might come with the trial.
• Find the terms and conditions for the offer. That includes offers online, on TV, in the newspaper, or on the radio. If you can't find them or can't understand exactly what you're agreeing to, don't sign up.
• Look for who's behind the offer. Just because you're buying something online from one company doesn't mean the offer or pop-up isn't from someone else.
• Watch out for pre-checked boxes. If you sign up for a free trial online, look for already-checked boxes. That checkmark may give the company the green light to continue the offer past the free trial or sign you up for more products — only this time you have to pay.
• Mark your calendar. Your free trial probably has a time limit. Once it passes without you telling the company to cancel your "order," you may be on the hook for more products.
• Look for info on how you can cancel future shipments or services. If you don't want them, do you have to pay? Do you have a limited time to respond?
• Read your credit and debit card statements. That way you'll know right away if you're being charged for something you didn't order.

If you see charges you didn't agree to, contact the company directly to sort out the situation. If that doesn't work, call your credit card company to dispute the charge. Ask the credit card company to reverse the charge because you didn't actively order the additional merchandise.