At the pharmacy counter you may be offered a generic version of your medicine, often at a fraction of the price. It is natural to wonder whether cheaper means weaker. For the vast majority of medicines, the answer from regulators is clear: an approved generic works the same way as the brand.
What a generic medicine is
When a company develops a new medicine it holds a patent for a number of years. After that, other manufacturers can make the same drug. To be approved, a generic must contain the same active ingredient, in the same strength and dosage form (tablet, capsule, inhaler and so on), and be taken the same way. Regulators such as the US Food and Drug Administration (FDA), the European Medicines Agency and the UK MHRA apply the same manufacturing quality standards to generic and brand-name factories.
What "bioequivalent" means
Generic makers must show their product is bioequivalent: in studies, the amount of drug that reaches the bloodstream and how quickly it gets there must fall within a tight statistical range of the original. A common myth is that this allows a generic to contain 20% less medicine. It does not. The range applies to the statistical confidence limits of the comparison, and in practice the average difference found in reviews of approved generics is very small.
Generic vs brand at a glance
- Active ingredient
- Identical
- Strength and dose form
- Identical
- Quality standards
- The same regulatory standards
- Inactive ingredients
- May differ: colour, shape, fillers, coatings
- Price
- Usually much lower once several makers compete
- Share of US prescriptions
- Around nine in ten are filled with generics
When switching needs care
Because inactive ingredients can differ, a small number of people react to a dye or filler, or find a new tablet harder to swallow. For a few narrow therapeutic index medicines, where small changes in blood levels matter, such as levothyroxine, warfarin, lithium and some anti-epileptic drugs, doctors may prefer you to stay on one manufacturer's version or check levels after a switch. If a medicine looks different from usual, ask your pharmacist; it is often just a different generic maker.
Biosimilars, versions of complex biological medicines such as insulin or antibody treatments, are approved through a separate process because they cannot be copied exactly, but they also have to show no meaningful difference in safety or effectiveness.
Cheap generics online: a warning
Legitimate generics come from licensed pharmacies with a prescription. Websites selling "generic" versions of popular prescription drugs with no prescription, often for erectile dysfunction, weight loss or hair loss, are a different story: many are unlicensed and some sell fakes. Our guide to buying medicines online safely explains how to tell the difference.
Based on guidance from: US Food and Drug Administration, European Medicines Agency, NHS.
