Generic Drugs: Answers to Common Questions

Medically Reviewed by Sabrina Felson, MD on March 05, 2024
5 min read

If you've had a prescription filled recently, there's a good chance you're taking a generic drug. Almost 80% of prescription drugs sold are generics. That option helps save patients and hospitals billions of dollars every year.

It's estimated that you could save at least two-thirds of your drug costs if you use generic drugs.

According to the FDA, generic drugs can be trusted to have the same quality as brand-name drugs -- but at a cheaper price. That's important to know because no one wants to skimp on health, even if it means saving money.


The FDA requires a generic drug to meet standards that ensure it's the same basic product as the brand-name drug. That means the generic drug is safe and can be taken:

  • The same way as a brand-name drug
  • For the same reason as a brand-name drug

For the FDA to approve a generic drug, it must be the same as the brand-name product in:

  • Active ingredient
  • Strength
  • Use and effect
  • How you take it (for example as a pill, inhaler, or liquid)
  • Ability to reach the required level in the bloodstream at the right time and to the same extent
  • Testing standards

Some differences between generics and brand-name drugs are allowed. These may change the look of the drug. But they don’t affect how it works or its safety.

Generic drugs may differ in:

  • Shape
  • Color
  • Packaging
  • Labeling (minor differences)

Generic drugs are allowed to have different inactive ingredients than brand-name drugs. For example, they may have a different:

  • Flavoring
  • Preservative

The inactive ingredients in a generic, though, must be considered safe by the FDA.

Generic drugs may also have a different expiration date than brand-name drugs. But even so, the generic must keep its effectiveness until its expiration date, just like a brand-name product.


You may be wondering how a generic drug can be sold at a much lower price than a brand-name drug.

The difference in price has to do with the different costs drugmakers have in bringing generics and brand-name drugs to the pharmacy shelf.

Making a new drug is expensive. A manufacturer's costs for the launch of a new drug include money for:

  • Research
  • Large-scale drug testing
  • Advertising, marketing, and promotion

The FDA has tried to balance the rights of the maker of brand-name drugs to recoup its investment with the rights of patients to have access to lower cost generic drugs. To help a drugmaker recover its costs, new brand-name drugs are given patent protection when they are first sold.

The patent gives a drugmaker exclusive rights to produce and sell the drug for a limited time. The average time a brand-name drug is protected by the patent after it hits the market is 12 years.

When the patent ends, other companies are allowed to make and sell a generic version. The generic drugmaker's costs are relatively low because the product has already been developed and tested by the brand-name company.

So makers of generic drugs can pass the savings along in the form of lower prices to pharmacies and ultimately to us. The competition among multiple companies producing a generic version of a drug also helps keep the price low.


Some groups have raised questions about the FDA requirements for proving a generic drug acts in the same way as the brand-name drug.

To prove a generic drug works the same way as a brand-name drug, the manufacturer needs to show there’s no significant difference in the rate and extent to which the drugs are absorbed into the body.

Scientists perform tests to measure this difference and describe the results in the form of a percentage. Most scientists agree that a 20% difference in the way a drug is absorbed is acceptable.

Some groups, though, claim that percentage is too large and could cause problems based on how much of the drug is in a person's system at any one time.

The FDA reports that there have been no recorded problems related to the variation in absorption for drugs that meet this requirement.

The FDA has conducted two large studies to learn the actual variation in absorption between brand-name drugs and their generic versions. The studies show that the average variation is 3.5%. That's a variation that can be expected even between two separate batches of the same brand-name or generic drug.


Some drugs -- known as NTI (narrow therapeutic index) drugs -- may need special consideration if you are thinking of using the generic version. NTI drugs have a narrow margin between the amount that is safe and effective and the amount that is toxic.

These generic drugs include:

While the FDA doesn’t have a policy restricting the use of NTI generics, some states have laws that do. In those states, if generics are used, precautions and additional monitoring are required.

The list of restricted NTI drugs varies from state to state. The FDA does not have a list of recognized NTI drugs. The FDA is revising its policy to identify drugs that should be included on such a list and to specify whether additional precautions are needed when generics are substituted for such drugs.

Your doctor should tell you if you are taking an NTI drug and what type of monitoring you need.


Generics are not available for all medications. The best way to find out if a generic is available for a medication you are taking -- and whether or not you should take it -- is to ask your doctor and pharmacist.

Some health insurance providers require you to use a generic drug, if available. If you choose to purchase the brand-name product, you may end up paying on your own or have a larger co-pay.

Generally, your pharmacist can substitute a generic drug for a brand-name drug. If a generic is available, but for some reason your doctor thinks you should still take the brand-name drug, they’ll write "Do Not Substitute" on the prescription.

If your pharmacist for some reason does not substitute a generic for a brand-name drug, you can ask your doctor to indicate on the prescription that substitutions are acceptable. That way, you can get the same drug for a lot less money.

It can get confusing. Don't be afraid to ask your pharmacist if the medication you received is the generic form of the medicine you are used to taking.

Tell your doctor if you notice any change in your condition or have any unusual side effects when changing from a brand-name to a generic drug.

And don't forget that nonprescription drugs may also be sold as generics. You might find them under the store's in-house label. They can also save you money.