Anti-VEGF is a type of medical therapy that blocks a protein your body uses to grow new blood vessels. The full name of that protein is vascular endothelial growth factor, and while it plays a normal role in healing and development, it can also fuel diseases when blood vessel growth spirals out of control. Anti-VEGF drugs are used most commonly to treat serious eye conditions and certain cancers.
How VEGF Works in the Body
Your body constantly manages the growth of blood vessels, a process called angiogenesis. VEGF is the main chemical signal that tells cells lining your blood vessels to multiply and form new branches. It also makes existing blood vessels more permeable, allowing fluid to leak through their walls more easily. In normal circumstances, this is useful: wounds need new blood supply to heal, and growing tissue needs oxygen delivery.
Problems arise when VEGF is overproduced. In the eye, excess VEGF triggers the growth of fragile, abnormal blood vessels that leak fluid and blood into delicate retinal tissue, destroying vision. In cancer, tumors hijack VEGF signaling to build their own blood supply, feeding themselves the oxygen and nutrients they need to keep growing and eventually spread. Anti-VEGF drugs work by binding to the VEGF protein (or its receptor on cells) and neutralizing it, effectively cutting off the signal that drives harmful blood vessel growth.
Eye Conditions Treated With Anti-VEGF
The most well-known use of anti-VEGF therapy is in ophthalmology. Wet age-related macular degeneration (wet AMD) is the condition that put these drugs on the map. In wet AMD, abnormal blood vessels grow beneath the retina and leak fluid, causing rapid central vision loss. Anti-VEGF injections stop those vessels from growing and reduce the leakage.
The results have been significant. In a major five-year study (the CATT Follow-up Study), 50% of treated eyes achieved 20/40 vision or better, which is sharp enough for most daily tasks including driving. About 42% of patients gained meaningful improvements in their vision, with roughly 18% gaining three or more lines on an eye chart. Before anti-VEGF therapy existed, wet AMD almost inevitably led to severe vision loss.
Beyond wet AMD, these drugs are also standard treatment for diabetic macular edema (swelling in the retina caused by diabetes), retinal vein occlusions (blockages in the blood vessels that drain the retina), and other conditions involving abnormal blood vessel growth in the eye.
Anti-VEGF in Cancer Treatment
Tumors cannot grow much beyond a tiny cluster of cells without building a blood supply. Anti-VEGF drugs exploit this dependency by starving tumors of oxygen and nutrients. Bevacizumab, the first anti-VEGF drug approved for cancer, works by binding to circulating VEGF before it can reach receptors on blood vessel cells. This halts new vessel formation and impairs the function of vessels the tumor has already built.
Bevacizumab is approved for use in colorectal cancer, non-small cell lung cancer, kidney cancer, ovarian cancer, and glioblastoma (an aggressive brain tumor), among others. It is typically given alongside chemotherapy rather than alone. There’s also a secondary benefit: by temporarily “normalizing” the chaotic blood vessels inside a tumor, anti-VEGF treatment may help chemotherapy drugs penetrate the tumor more effectively.
Current Anti-VEGF Medications
Several FDA-approved anti-VEGF drugs are in use today, mostly differentiated by how they’re delivered and how long they last:
- Ranibizumab (Lucentis): One of the earliest eye-specific anti-VEGF drugs, designed as a smaller antibody fragment that penetrates retinal tissue well.
- Aflibercept 2 mg (Eylea): A fusion protein that traps VEGF, widely used for multiple retinal conditions.
- Aflibercept 8 mg (Eylea HD): A higher-dose version that allows longer intervals between injections.
- Faricimab (Vabysmo): A newer drug that blocks both VEGF and a second pathway involved in blood vessel instability.
- Brolucizumab (Beovu): A smaller molecule that can be delivered at higher concentrations.
- Bevacizumab (Avastin): Approved for cancer, but widely used off-label as a lower-cost eye injection.
Biosimilar versions are also reaching the market. The FDA approved a biosimilar of ranibizumab in late 2025, and an aflibercept biosimilar followed shortly after, both of which could lower treatment costs.
What the Eye Injection Is Like
For eye conditions, anti-VEGF drugs are delivered through an intravitreal injection, meaning a very fine needle is inserted directly into the gel-filled center of the eye. The procedure takes only a few minutes but involves several steps: numbing drops, an antiseptic flush to prevent infection, a small device (speculum) to hold the eyelids open, and then the injection itself.
In patient surveys, the needle entry itself ranked as the single most unpleasant moment, but the combined discomfort of the draping and speculum steps actually accounted for more overall unpleasantness. Patients frequently reported that even after many injections, the experience didn’t get significantly easier emotionally, particularly the moment of seeing the needle approach. That said, actual pain is usually mild and brief thanks to the numbing drops.
How Often Injections Are Needed
Treatment typically starts with a loading phase of monthly injections for the first three months. After that, the schedule depends on which dosing strategy your doctor uses.
With a “treat and extend” approach, you receive an injection at every visit, but the time between visits is gradually lengthened as long as your condition stays stable. In one study, patients averaged about 8 injections in the first year and 3 to 4 in the second year. With an “as needed” (pro re nata) approach, you’re monitored monthly but only injected when signs of disease activity appear, which resulted in fewer injections (around 5 in the first year) but the same number of clinic visits for monitoring.
Newer drugs are pushing treatment intervals further apart. Clinical trials have shown that agents like faricimab, brolucizumab, and high-dose aflibercept can maintain vision with injections as infrequently as every 16 weeks (about four months) for some patients, a meaningful improvement over the monthly or bimonthly schedules that older drugs require.
Risks and Side Effects
The most common side effect of eye injections is minor bleeding on the white of the eye (subconjunctival hemorrhage), which occurs in about 10% of injections and looks alarming but is harmless and resolves on its own. It’s more frequent in people taking aspirin or blood thinners.
Serious complications are rare. Endophthalmitis, a severe infection inside the eye, occurs in roughly 0.02% to 1.6% of patients across clinical trials. Significant inflammation inside the eye happens in 1% to 3% of cases with some drugs, though rates vary by medication. Retinal detachment following injection is uncommon, reported at 0% to 0.67%.
For cancer patients receiving intravenous bevacizumab, side effects differ and can include high blood pressure, increased risk of bleeding, slow wound healing, and in rare cases, bowel perforation or blood clots. These risks are managed through monitoring during treatment.