The short answer
What to do about a forgotten dose depends on which medicine you are taking. MedlinePlus tells capecitabine users to skip the missed dose entirely, while anastrozole users may take it unless the next dose is nearly due. One instruction is constant across all three: never take a double dose.
There is no single missed-dose rule for cancer pills — check your own drug's instructions.
For capecitabine, MedlinePlus says to skip the missed dose and carry on as normal.
For anastrozole, MedlinePlus says to take it when you remember unless the next dose is almost due.
For cabozantinib, MedlinePlus says to skip it if the next dose is less than 12 hours away.
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The full explanation.
First, breathe
Realising at bedtime that this morning's tablet is still in the packet is a horrible feeling. It usually arrives with a rush of guilt and a fear that you have damaged your own chances.
Federal drug information does not treat a single missed dose as a catastrophe. It treats it as something to handle correctly. The catch is that "correctly" is different for different medicines, so the instruction you half-remember from a friend's treatment may be wrong for yours.
Three drugs, three answers
Capecitabine. MedlinePlus is unambiguous here: skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
Anastrozole. MedlinePlus gives more latitude. Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule.
Cabozantinib. MedlinePlus sets an explicit gap. Take the missed dose as soon as you remember it, but if it is less than 12 hours until your next scheduled dose, skip it and continue as normal.
Notice what changes and what does not. The rule about whether to take the late dose varies. The rule about doubling up never does.
If you remember nothing else from this page, remember that catching up by taking two is not an option in any of these instructions.
Finding the rule that applies to you
Your medicine's own instructions are the ones that count.
- The leaflet dispensed with your prescription contains a missed-dose section. Keep it rather than binning it with the packaging.
- MedlinePlus publishes a drug information page for individual medicines by name, with a "what should I do if I forget a dose" section.
- Your oncology pharmacist can answer in a minute over the phone, and this is exactly the sort of call that service exists for.
Write the answer down somewhere findable — inside a cupboard door, in your phone notes, on the box. At two in the morning you will not want to be searching.
Stopping it happening again
Occasional forgetting is human. A pattern of forgetting is a practical problem with practical solutions.
- Set repeating alarms rather than relying on remembering.
- Tie doses to fixed daily events so the cue is behavioural, not mental.
- Ask about a pill organiser, checking first that it is suitable for your particular tablets.
- Tell someone at home what your schedule is, so there is a second pair of eyes.
- If side effects are the real reason you are avoiding doses, say that plainly at your next appointment. Quietly skipping is a much worse outcome than a conversation about managing side effects or adjusting the plan.
What not to do
Do not take extra to compensate. Do not stop the medicine because you have missed some and feel you have ruined it. Do not swap to a schedule that suits you better without telling anyone.
And do not carry the guilt alone. Bring it up at your next visit. Teams would far rather hear "I missed four doses last month, here is why" than discover a pattern later.
Words to know
Tap any term to see what it means.
Common questions
Is one missed dose serious?
MedlinePlus gives calm, practical instructions for each drug rather than emergency ones, which tells you a single miss is a known and manageable event. If missed doses are becoming frequent, that is worth raising with your team.
Why can't I just take two next time?
Because the drug information says not to. MedlinePlus repeats the same sentence across capecitabine, cabozantinib and anastrozole: do not take a double dose to make up for a missed one.
How do I know which rule applies to me?
Read the leaflet that came with your prescription, or look up your exact drug name on MedlinePlus. If you are not certain, phone your oncology pharmacist before the next dose is due.
What if I threw up shortly after swallowing it?
That is not the same as a missed dose, and the pages here do not answer it. Contact your care team for instructions rather than deciding yourself.
Questions to ask your doctor
Being prepared helps you get the most out of your appointments. Save or print these questions.
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Your next step
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Sources last checked: 2026-08-11 what this meansLast updated: 2026-08-11Next planned review: 2027-08-11
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How this page was created
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. We do not employ clinicians and do not intend to — our work 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 checked line by line against the sources listed on it. That confirms the sources support what the page says. 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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