The short answer
Tears are made all the time and normally drain away through small ducts. NCI says some types of chemotherapy can clog those ducts, causing watery eyes and blurry vision. Contact lenses may become uncomfortable during treatment.
NCI states that some types of chemotherapy can clog your tear ducts.
Clogged tear ducts can cause blurry vision and watery eyes.
Contact lens discomfort is described as possible during chemotherapy.
Watering eyes are not a sign that you are producing more tears than usual, but that they are not draining.
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The whole article, with every detail and caution.
This page is for people whose eyes started watering during chemotherapy. It explains why it happens, why it is worth mentioning, and which eye changes need a quick call.
The short explanation
Your eyes are not producing a flood of extra tears. The tears you always made are no longer draining away.
NCI's chemotherapy guide puts it directly: some types of chemotherapy can clog your tear ducts, which can cause blurry vision and watery eyes.
Tear ducts are tiny channels at the inner corner of each eye. They carry tear fluid down into the nose, which is why a good cry leaves you sniffing. When those channels narrow or block, tears have nowhere to go but over the lower lid and down your cheek.
Understanding this changes how the symptom feels. It is a plumbing problem, not an emotional one.
Why it is more than a nuisance
Many people think of this as mildly embarrassing, not medical, so they do not mention it.
But NCI links the same clogged ducts to blurry vision. NCI's booklet says that if your vision gets blurry or your eyes water more than usual, you should tell your doctor or nurse.
Contact lenses
NCI names contact lens discomfort as something that can happen during chemotherapy.
NCI says some types of chemotherapy can bother your eyes and make wearing contact lenses painful. NCI's booklet says to ask your doctor or nurse whether you can wear contact lenses while getting chemotherapy.
Practical things people do
NCI's booklet does not give a long self-care list for watery eyes specifically, and we are not going to invent one.
What it does support is telling your team. They know which drugs you are on and whether eye effects are expected with those drugs. They can also tell you whether eye drops are appropriate for you, which is not a decision to make in a pharmacy aisle while on chemotherapy.
A few things are simply sensible while you wait: carry tissues, keep a spare pair of glasses somewhere useful, and do not rub your eyes with unwashed hands.
What to raise urgently
NCI's booklet does contain a broader instruction that is relevant here: let your doctor or nurse know right away if you notice any nervous system changes.
NCI's booklet does not list vision among its nervous system changes, so do not wait on this point. MedlinePlus lists sudden changes in vision, including color vision, loss of vision and eye pain among the symptoms to report to your doctor immediately for cisplatin, one chemotherapy drug. Sudden vision changes are not the same as eyes that have been gently watering for a couple of weeks. Call your care team the same day. If you cannot reach them, go to an emergency department or call 911.
Bringing it up
At your next visit, describe the pattern. Both eyes or one. All day or worse at certain times. Whether reading has become harder. Whether the watering is enough that it runs down your face in cold air or wind.
That detail helps your team tell a drug effect from something else. It takes only a few seconds to say.
When to get help sooner
- Call your care team right away, the same day, if your vision changes suddenly, you lose vision, or your eye hurts. MedlinePlus lists these among the cisplatin effects to report to your doctor immediately. If you cannot reach your team, go to an emergency department or call 911.
- Call your care team within a day or two if your vision has turned blurry or your eyes are watering more than usual — NCI's booklet asks you to tell your doctor or nurse when either of those happens, rather than waiting for your next scheduled visit.
Common questions
Am I crying more, or is something blocked?
NCI's explanation points to drainage. It says some chemotherapy can clog the tear ducts, which causes watery eyes and blurry vision. Your eyes are making tears at their usual rate, but the plumbing that carries them away is not working properly.
Can I keep wearing my contact lenses?
NCI notes contact lens discomfort as a possible effect during chemotherapy. Ask your team or your eye doctor what they advise for you.
Is blurry vision from this serious?
NCI links blurry vision here to clogged tear ducts. That said, vision changes have other possible causes during cancer treatment, so tell your team what you are experiencing rather than deciding the cause yourself.
Does it go away?
NCI's chemotherapy booklet does not give a timeline for this. Your oncology team can tell you whether the specific drugs you are on are known for it and what they expect.
Questions to ask your doctor
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Sources last checked: 2026-08-11 what this meansLast updated: 2026-10-01Next planned review: 2027-08-11
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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