Before starting a steroid, ask your doctor or pharmacist to check every prescription, over-the-counter medicine, vitamin, and herbal product you use. The main groups to review include ibuprofen or aspirin, blood thinners such as warfarin, diabetes medicines, water tablets, certain antibiotics and antifungals, some HIV medicines, seizure medicines, and vaccines. The level of risk depends on the exact steroid, dose, how you take it, treatment length, and your other medicines.
Which types of steroids can interact with chronic medicines?
In this article, “steroids” means corticosteroids, medicines used to reduce inflammation or control immune system activity. Common examples include prednisolone, prednisone, dexamethasone, methylprednisolone, and hydrocortisone. These medicines are different from anabolic steroids used to build muscle.
Interactions are particularly important to review when corticosteroids are taken as tablets or injections because they can affect the body beyond the area being treated. Inhalers, nasal sprays, and skin creams should also be included in your medication list, especially if you use several steroid products or use them regularly at high doses.
An interaction does not always mean two medicines cannot be taken together. Sometimes the combination is appropriate with additional monitoring or a change in the prescribed dose. The important step is to identify the exact medicines and check how they may affect one another.
Which painkillers and blood thinners need special attention?
Ibuprofen, naproxen, and aspirin
Nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen and naproxen, can increase the risk of stomach and intestinal side effects when taken with oral corticosteroids. These effects may include stomach irritation, ulcers, or bleeding. Aspirin can also be relevant, including when it is prescribed at a low dose to help prevent heart attacks or strokes. DailyMed's prednisone prescribing information describes the increased risk of gastrointestinal side effects with aspirin and other NSAIDs. Do not stop prescribed aspirin on your own, but ask a healthcare professional before adding a painkiller.
Warfarin and other anticoagulants
Warfarin is an anticoagulant, commonly called a blood thinner. Corticosteroids can change its effect, and the direction or size of the change is not always predictable. The prednisone prescribing information notes conflicting reports but recommends frequent checks of blood-clotting measures when warfarin and corticosteroids are used together. Your anticoagulation team may need to arrange additional international normalized ratio (INR) tests when steroid treatment starts, changes, or ends.
If you use another anticoagulant or an antiplatelet medicine, such as clopidogrel, mention it during your medication review. The interaction and bleeding risks depend on the exact combination, so do not assume that a medicine is safe simply because it is not warfarin. Do not change or stop a blood thinner without instructions from the clinician managing it.
Can steroids affect diabetes medicines?
Yes. Corticosteroids can raise blood glucose, or blood sugar, which may make existing diabetes harder to control. This can affect people using insulin as well as those taking tablets or other medicines for diabetes. Some people need more frequent glucose checks or a temporary change to their diabetes treatment while taking steroids.
The University College London Hospitals NHS Foundation Trust guidance on steroid-related diabetes explains that steroid treatment can increase glucose levels and that diabetes care may need to be reviewed during treatment. Tell your diabetes team when you start a steroid, when the dose changes, and when treatment is reduced or stopped. Do not adjust insulin or diabetes tablets without an agreed plan, because your medicine needs may change as the steroid dose changes.
If you monitor glucose at home, follow the schedule recommended by your healthcare team. Increased thirst, passing urine more often than usual, or unusually high glucose readings are reasons to contact your care team for advice. Your existing diabetes plan may need to be adapted to the steroid course.
What should you check if you take blood pressure or heart medicines?
Some corticosteroids can cause the body to retain salt and fluid, raise blood pressure, or lower potassium levels. These effects can be more important for people with high blood pressure, heart failure, kidney problems, or a history of heart rhythm disturbances. The risk depends on the specific steroid, its dose, and how long it is used.
Water tablets, also called diuretics, deserve particular attention. Some diuretics can lower potassium, and corticosteroids may add to that effect. Depending on the medicines and your medical history, your clinician may recommend checking blood pressure, swelling, or blood potassium levels. Do not start potassium supplements or change a diuretic dose without professional advice.
Tell the prescribing clinician about all medicines used for blood pressure, heart failure, or abnormal heart rhythms. A combination may still be suitable, but the treatment plan may need closer review, especially when a steroid course is prolonged or uses a higher dose.
Can antibiotics, antifungals, or seizure medicines change steroid levels?
Some medicines change how quickly the liver breaks down corticosteroids. This can increase the amount of steroid in the body or reduce its effect. These interactions depend on the particular drugs and are not the same for every corticosteroid.
- Some antifungal medicines: Ketoconazole and itraconazole can slow the breakdown of certain corticosteroids, potentially increasing steroid exposure.
- Some antibiotics: Clarithromycin and erythromycin can affect steroid breakdown and may increase corticosteroid levels.
- Some HIV medicines: Ritonavir and related medicines may affect the way certain corticosteroids are processed.
- Some seizure medicines: Phenytoin, carbamazepine, and phenobarbital can speed up the breakdown of certain corticosteroids, potentially reducing their effect.
- Some antibiotics used for tuberculosis: Rifampin can also speed up steroid breakdown and may mean that the treatment plan needs review.
The official prednisone product information on DailyMed describes interactions with medicines that inhibit or increase the activity of the CYP3A4 enzyme, which helps process many drugs. A clinician or pharmacist can check whether the interaction applies to your specific steroid, whether any monitoring is needed, and whether the dose or choice of medicine requires review. Do not change an antibiotic, antifungal, seizure medicine, or steroid dose yourself.
What about other immune-suppressing medicines and vaccines?
Corticosteroids can reduce immune system activity. If you also take a medicine that suppresses the immune system, such as a transplant medicine or certain treatments for an autoimmune condition, tell the prescribing clinician. The combination may require an individual review of infection risk and monitoring.
Vaccines also need to be considered. Some live vaccines may not be suitable while a person is taking an immunosuppressive dose of a corticosteroid. Other vaccines may still be appropriate, although the immune response can depend on the treatment and the person's health. The NHS guidance on prednisolone advises people to tell their doctor or nurse about steroid treatment before having a vaccination. Check with your healthcare professional before arranging a vaccine, rather than assuming that every vaccine is unsafe.
Do herbal products and non-prescription medicines need to be checked?
Yes. An interaction check should include more than prescription medicines. Over-the-counter painkillers, cold and flu products, vitamins, supplements, and herbal remedies can all be relevant. For example, St John's wort and cimetidine are listed among products that may interact with prednisone. Evidence about many herbal products and their combinations with corticosteroids is limited, so a lack of a known interaction should not be taken as proof of safety.
The NHS advice on prednisolone and other medicines or herbal supplements recommends checking before adding medicines that could affect treatment or increase side effects. Share the ingredient list or packaging with your pharmacist when a product contains several active ingredients or when you are unsure whether it includes a painkiller.
How can you get a safe interaction check?
Prepare a complete list of what you take before starting a steroid or collecting a new prescription. Include medicine names, doses, how often you take them, and the reason for taking them if known. Include medicines prescribed by different doctors as well as products bought from a pharmacy, supermarket, or online store.
- Tell the clinician or pharmacist which steroid you have been prescribed, including its strength, form, dose, and planned duration.
- Explain whether any medicine has recently been started, stopped, or changed, including antibiotics, antifungals, diabetes medicines, blood thinners, and seizure medicines.
- Ask whether you need extra blood tests, glucose checks, blood pressure checks, or other monitoring during treatment.
- Check before starting a new painkiller, herbal remedy, supplement, or vaccine while taking the steroid.
- Ask what to do if the steroid dose is reduced or the treatment course ends, especially if your diabetes or anticoagulant treatment may also need review.
Do not stop long-term corticosteroids suddenly or make unsupervised dose changes. After some courses, the dose needs to be reduced gradually, and stopping can also change how other medicines should be managed. Follow the tapering instructions provided by your prescriber.
Get urgent medical help if you vomit blood, pass black or tarry stools, or experience significant unexplained bleeding while taking medicines that can increase bleeding risk. For other concerning changes after starting or changing a medicine, contact your healthcare professional promptly and provide the names and doses of the medicines involved.
Why is the exact steroid and dose important?
Two people taking medicines from the same general group may need different advice because they use different corticosteroids, doses, or treatment durations. A short course of tablets, a long-term oral prescription, and an inhaled or topical preparation do not necessarily carry the same interaction risks. Other factors, such as kidney or liver problems and the reason for each prescription, can also affect the review.
The safest approach is to have the exact combination checked rather than relying on a general list of medicines to avoid. A pharmacist can often perform this check using your complete medication list and clarify whether you need a monitoring plan or advice from the clinician who prescribed the steroid.