Rick Roberts knows first-hand about counterfeit drugs.
Roberts, an AIDS patient, questioned his pharmacist after injecting himself with a drug that was supposed to help him keep weight on. Almost immediately, he felt painful stinging. He soon found out that the medication was counterfeit.
"For me, the most present problem was not knowing and having nightmares about what was in the vials that I injected," Roberts said.
The nearly identical-looking counterfeit was a fertility drug. Luckily, it was discovered before doing any harm.
Counterfeiters often copy drugs that are expensive or popular. That has included Viagra and the cholesterol-lowering drug Lipitor. The Food and Drug Administration estimates that 1 percent of prescription drugs may be counterfeit.
"They're looking for the best profits -- either very expensive biotechnology drugs, injectable drugs, or big volume sellers like Lipitor, which is the number-one selling drug in America," said Katherine Eban, an investigative journalist and author of the book "Dangerous Doses: How Counterfeiters are Contaminating America's Drug Supply." "Generally, those are the targets of counterfeiters."
Eban said if they are careful, patients can often spot imposters on their own. In fact, that is how most counterfeit medications are detected.
"When you're taking pills, put them in the palm of your hand and look at them in the light," she said. "See if they look different. Notice packaging differences and notice strange side effects. Is anything different? If you're taking injectible medicine, do you feel a stinging upon injection? A rash at the injection site? That way, if you see something that is unusual, you can talk to your pharmacist.
If people suspect that they are taking fake medicine, Eban said they should first visit their pharmacist, who often gets alerts from drug makers about whether counterfeits exist on the market. She added that most drug manufacturers have 1-800 numbers for customer complaints.
A new FDA action will crack down on counterfeits by tracking drugs every step of the way. Drugs move from manufacturers through a maze of wholesalers, then on to the pharmacy. Counterfeits can slip in.
Wholesalers will now be required to keep a detailed record tracking the drug's history and who handled it at each step of the process.
"I think it will make a dent," said Margaret Glavin, the associate commissioner of the FDA. "It will make it harder for counterfeit drugs to enter the legitimate supply chain."
Robert Drucker, owner of RxUSA Wholesale Inc., a New York wholesale company, says he will have his tracking system in place by next month.
"The consumer will know with a greater degree of safety that he's buying what he thinks he's getting," said Drucker.
In the last two years, the FDA has pursued 90 cases of counterfeit drugs. They say that's just the beginning.
Eban said that the major drug store chain CVS is fighting back against counterfeit drugs.
"CVS announced they were no longer going to buy from wholesalers who bought from, sometimes, the shady gray market of secondary wholesalers," she said. "In other words, they only want to do business with wholesalers who are buying directly from the manufacturer. That's an important step in cracking down on this problem."
ABC News' Lisa Stark contributed to this report