Yes, Roundup is a herbicide. It is one of the most widely used weed-killing products in the world, sold for both residential and agricultural use. For decades, its primary active ingredient was glyphosate, a broad-spectrum chemical that kills nearly any plant it contacts. However, the Roundup brand has changed significantly in recent years, and the bottle you pick up at a hardware store today likely contains no glyphosate at all.
How Roundup Works as a Herbicide
Glyphosate, the chemical that made Roundup famous, kills plants by blocking a specific enzyme they need to produce three essential amino acids. Without those amino acids, the plant can’t build proteins, and it dies. This pathway exists in plants and some microorganisms but not in mammals, which is one reason glyphosate was long considered relatively safe for people and animals.
Roundup is classified as a non-selective herbicide, meaning it doesn’t discriminate between weeds and desirable plants. Spray it on your lawn and it will kill the grass along with the dandelions. That’s why traditional Roundup was designed for use on driveways, fence lines, garden beds before planting, and other areas where you want to eliminate all vegetation. In agriculture, it’s paired with genetically engineered “Roundup Ready” crops that tolerate glyphosate, allowing farmers to spray entire fields and kill only the weeds.
Once glyphosate reaches the soil, it breaks down through natural microbial activity. Its average half-life in soil is about 60 days, according to EPA data, meaning half the applied chemical degrades within roughly two months.
Roundup Has Changed Since 2024
If you’re shopping for Roundup today, you should know that Bayer (the company that now owns the brand) has removed glyphosate from all residential Roundup products. The name on the bottle is the same, but the chemicals inside are different.
The current flagship product, Roundup Weed and Grass Killer Exclusive Formula, uses a combination of three active ingredients: triclopyr, fluazifop, and diquat. Triclopyr targets broadleaf weeds. Fluazifop targets grasses. Diquat is a fast-acting, non-selective herbicide that kills green vegetation through a different mechanism than glyphosate. Together, they cover a similar range of weeds but work in fundamentally different ways.
Other Roundup-branded products have become even more specialized:
- Roundup for Lawns is a selective herbicide that kills weeds without harming lawn grass. It has never contained glyphosate, even before the reformulation.
- Roundup Dual Action formulas add a longer-lasting ingredient called imazapic that prevents new weeds from sprouting for months after application.
- Roundup Landscape Weed Preventer is a granular product that stops weeds before they emerge, using yet another active ingredient entirely.
This means “Roundup” is no longer a single product with a single active ingredient. It’s a brand name applied to more than a dozen different herbicide formulations. Reading the label matters more than it used to.
The Cancer Debate Around Glyphosate
Glyphosate remains at the center of a significant scientific disagreement. In 2015, the International Agency for Research on Cancer (IARC), a branch of the World Health Organization, classified glyphosate as “probably carcinogenic to humans.” That classification was based on limited evidence of cancer in people exposed to the chemical in real-world settings and stronger evidence from animal studies.
The U.S. Environmental Protection Agency reached the opposite conclusion. After reviewing 15 animal carcinogenicity studies (compared to the eight IARC evaluated), the EPA determined that glyphosate is “not likely to be carcinogenic to humans.” The agency also found no evidence that glyphosate disrupts hormones and no indication that children are more sensitive to it than adults.
These two assessments used different methodologies and different datasets, which explains how two credible organizations arrived at conflicting answers. The EPA’s 2020 interim decision on glyphosate was partially vacated by a federal appeals court in 2022, and the agency is currently working toward a final registration review decision. Glyphosate remains legal for agricultural use in the United States, though the residential shift away from it has already happened through Bayer’s reformulation.
Why It Still Matters for Home Users
Even though residential Roundup no longer contains glyphosate, the new formulations come with their own considerations. Diquat, for instance, is a contact herbicide that burns plant tissue on the surface rather than moving through the plant’s internal system the way glyphosate did. This means it works faster (you’ll see browning within hours), but it may not kill deep-rooted perennial weeds as thoroughly, since the roots can survive and regrow.
The new formulas also include selective herbicides mixed with non-selective ones, which changes how the product behaves. Fluazifop kills grasses but leaves broadleaf plants unharmed, while triclopyr does the opposite. The combination covers both categories, but each ingredient has different rainfast windows and absorption rates. Heavy rain within two hours of application can wash herbicides off foliage and require a repeat treatment.
If you still want glyphosate specifically, it remains available in agricultural and commercial-grade products, as well as some generic brands sold at garden centers. But anything sold under the Roundup name for home use now relies on different chemistry entirely.