Guide
What is a contraindication?
A contraindication is a condition or circumstance in which a medicine, vaccine, test or procedure should not be used, because the risk of harm outweighs the likely benefit for that person. An absolute contraindication generally means the intervention should not be used in that situation; a relative contraindication means the potential benefit may sometimes justify proceeding despite increased risk, a judgement a clinician makes case by case.
This is information about reading evidence, not medical advice. Talk to your doctor or pharmacist before changing anything.
The definition regulators use
For prescription drug labels in the US, the Food and Drug Administration's labelling rule says the Contraindications section "must describe any situations in which the drug should not be used because the risk of use (e.g., certain potentially fatal adverse reactions) clearly outweighs any possible therapeutic benefit" (21 CFR 201.57(c)(5)).
For vaccines, the US Centers for Disease Control and Prevention (CDC) defines contraindications as "conditions in a recipient that increases the risk for a serious adverse reaction," and says a vaccine should not be given when one is present.
The idea is the same in both: a contraindication is about the balance of risk and benefit for a particular person in a particular situation. It is not a judgement that a medicine is unsafe for everyone.
Absolute vs relative contraindications
These two terms are widely used in clinical practice and teaching. They are not formal regulatory categories, so read them as a scale rather than a legal line.
| Absolute contraindication | Relative contraindication | |
|---|---|---|
| Meaning | Do not use. The risk is judged too high in that situation. | Use with caution, or only if the benefit is judged to outweigh the risk. |
| Who decides | Usually settled in the product information or guideline. | A clinician, weighing the individual case. |
| Nearest formal term | "Contraindication" (CDC; drug labels) | "Precaution" (CDC); "Warnings and precautions" (US drug labels) |
The CDC's vaccine guidance shows the distinction clearly. A contraindication means the vaccine should not be given. A precaution is a condition that "might increase the risk for a serious adverse reaction, might cause diagnostic confusion, or might compromise the ability of the vaccine to produce immunity." In general vaccination is deferred when a precaution is present, but "might be indicated" if the benefit outweighs the risk. That is close to what many clinicians mean by a relative contraindication.
Examples
These examples come from published public-health guidance. They illustrate the idea. They are not advice for any individual.
- Anaphylaxis after a previous dose of a vaccine. The Australian Immunisation Handbook says anaphylaxis to a previous dose "is a contraindication to receiving the same vaccine," and advises seeking further medical advice. It also notes that some people may still be able to receive the vaccine after specialist review, which shows how even firm contraindications are assessed case by case.
- Influenza vaccines. The Handbook lists the only absolute contraindications to influenza vaccines as anaphylaxis after a previous dose of any influenza vaccine, or after any component of an influenza vaccine.
- Live vaccines and severe immunodeficiency. The CDC states that severely immunocompromised people generally should not receive live vaccines, and that MMR vaccine should not be given to severely immunocompromised people.
- A temporary contraindication. The CDC notes that "the majority of contraindications are temporary," so a vaccine can often be given later once the condition has passed.
- A precaution, not a contraindication. A moderate or severe acute illness, with or without fever, is listed by the CDC as a precaution for all vaccines: vaccination is usually deferred until the person is better.
What a medicine label says: one example
Prescription medicines carry their contraindications in the official product information. As an illustration of how a label words them, the current US FDA-approved prescribing information for Viagra (sildenafil citrate) lists, under section 4 Contraindications, use in patients taking "nitric oxide donors such as organic nitrates or organic nitrites in any form either regularly and/or intermittently," because the medicine "was shown to potentiate the hypotensive effects of nitrates" (that is, the combination can lower blood pressure further). The same section also lists known hypersensitivity to sildenafil and use with guanylate cyclase stimulators such as riociguat.
This shows what a label says. It is not treatment or dosing guidance, and Australian product information may be worded differently. Check the Consumer Medicine Information (CMI) for your own medicine, and ask your pharmacist or doctor how it applies to you.
The CDC also lists conditions that are often wrongly treated as contraindications, such as a mild illness. Getting this wrong in either direction has costs, which is why the source matters.
Contraindication vs side effect vs interaction
- A side effect (adverse effect) is something a medicine may cause in anyone who takes it.
- A contraindication is about the person or situation: a condition, another treatment, or a history that makes use too risky.
- A drug interaction is a specific kind of problem where two substances affect each other. Some interactions are severe enough to be listed as contraindications.
Where to find contraindications for a medicine
- In Australia: prescription medicines have Product Information (PI) for health professionals, which includes a Contraindications section, and Consumer Medicine Information (CMI) written for patients. Your pharmacist can give you the CMI.
- In the US: the prescribing information (the "label") has a Contraindications section required by 21 CFR 201.57.
- Vaccines: the Australian Immunisation Handbook, or the CDC's contraindications and precautions tables.
- Your pharmacist and doctor. They know your history, your other medicines and your conditions. A list on paper cannot do that.
If you think a contraindication applies to you, do not stop or change a medicine on your own. Ask your doctor or pharmacist first.
For professionals: checking a contraindication claim in the literature
A medico-legal report, a guideline summary or a review might say a treatment is "contraindicated in" a group of patients. The questions worth asking are about the source:
- Where does the claim come from? Product information, a guideline, a trial, or a case report?
- Does the cited paper actually say it? A cited paper may report a single case, an association, or a caution, which is not the same as a contraindication.
- Is it absolute or relative in the source? Reports sometimes harden "use with caution" into "contraindicated", or soften the reverse.
- Is the source current? Labels and handbooks change. Check the date.
This is where MIA can help. Put the cited paper on the desk and ask whether it supports the contraindication as stated. The working separates what the paper shows, what may be drawn from it, and what it does not establish. Clinical Conservative is the default, so standard of care stays apart from investigational claims. MIA is not a clinician and gives no dosing or individual advice. Check a cited paper with MIA: 150 free credits, no card.
FAQ
What does contraindicated mean? It means a medicine, vaccine, test or procedure should not be used in a particular situation, because the risk of harm outweighs the likely benefit for that person.
What is the difference between an absolute and a relative contraindication? An absolute contraindication generally means the intervention should not be used in that situation. A relative contraindication means the potential benefit may sometimes justify proceeding despite increased risk; a clinician weighs that for the individual case.
Is a contraindication the same as a side effect? No. A side effect is something the medicine may cause. A contraindication is a condition or circumstance in the person that makes using the medicine too risky.
Where can I find the contraindications for my medicine? In Australia, in the Consumer Medicine Information (CMI) from your pharmacist, or the Product Information (PI) for health professionals. Ask your pharmacist or doctor how it applies to you.
This is information about reading evidence, not medical advice. Talk to your doctor or pharmacist before changing anything.
Sources
- Electronic Code of Federal Regulations (US). 21 CFR 201.57, Specific requirements on content and format of labeling for human prescription drug and biological products, paragraph (c)(5) Contraindications. accessed 22 Oct 2026.
- Centers for Disease Control and Prevention (US). Contraindications and Precautions, General Best Practice Guidelines for Immunization. updated 25 July 2024; accessed 22 Oct 2026.
- Australian Government Department of Health, Disability and Ageing. Australian Immunisation Handbook: Preparing for vaccination. last updated 30 Sep 2026; accessed 22 Oct 2026.
- Australian Government Department of Health, Disability and Ageing. Australian Immunisation Handbook: Influenza (flu). last updated 30 Sep 2026; accessed 22 Oct 2026.
- US National Library of Medicine, DailyMed (FDA-approved labeling). VIAGRA (sildenafil citrate) tablet, film coated: prescribing information, section 4 Contraindications. label version 32 published 13 Feb 2026; accessed 22 Oct 2026.
- Therapeutic Goods Administration (Australia). Product Information (PI). last updated 16 Feb 2023; accessed 22 Oct 2026.
- Therapeutic Goods Administration (Australia). Consumer Medicine Information (CMI). last updated 27 Aug 2020; accessed 22 Oct 2026.