Introduction
Over-the-counter medicines can make it easier to manage everyday symptoms such as headaches, colds, allergies, indigestion and minor pain without needing a prescription.
However, the fact that a medicine can be purchased without a prescription does not automatically mean it is suitable to take alongside every prescription medicine.
Some medicines can affect how other medicines work, increase the chance of side effects or contain the same active ingredient as another product you are already taking. Vitamins, herbal remedies and supplements can also interact with prescribed medicines. NHS guidance therefore recommends telling your doctor or pharmacist about all medicines, vitamins, supplements and herbal products you take.
This guide explains what you should check before combining an over-the-counter medicine with prescription treatment.
What Is an Over-the-Counter Medicine?
An over-the-counter, or OTC, medicine is a medicine that can be obtained without an individual prescription.
Some medicines for minor health problems can be bought directly from supermarkets, shops or pharmacies. Other medicines are available without a prescription but must be supplied under a pharmacist’s supervision.
Examples of OTC products can include medicines for:
- Pain
- Colds and coughs
- Allergies
- Indigestion
- Constipation
- Minor skin problems
- Travel sickness
Even though these products do not always require a prescription, they should still be used according to the instructions on the packaging or patient information leaflet.
Can You Take OTC Medicines with Prescription Medicines?
Sometimes you can, but it depends on the exact medicines involved.
There is no single rule that says every OTC medicine is either safe or unsafe with prescription treatment.
A pharmacist may need to consider:
- The prescription medicines you already take
- The OTC medicine you want to use
- The dose
- Other medicines or supplements you use
- Your health conditions
- Whether two products contain similar ingredients
- Whether combining the medicines could increase side effects
If you are unsure, Biscot Pharmacy’s local pharmacy in Luton can help you check whether an OTC product is suitable alongside your current medicines.
Why Can Medicines Interact with Each Other?
A medicine interaction occurs when one medicine affects another medicine or when combining medicines changes their effects.
This can sometimes:
- Increase side effects
- Make side effects more noticeable
- Change how a medicine works
- Affect how another medicine is absorbed
- Cause problems when products contain overlapping ingredients
NHS medicine guidance regularly advises patients to tell their pharmacist or doctor about other medicines they take because some combinations may require additional care.
Always Check the Active Ingredients
One of the easiest mistakes to make is taking two products containing the same active ingredient.
This can happen because different medicines are sold under different brand names or because a cold, flu or allergy product contains several ingredients in one product.
For example, NHS guidance warns that some promethazine products already contain paracetamol. Taking another paracetamol-containing medicine at the same time could result in taking too much paracetamol.
Before combining medicines:
- Read the label
- Check the active ingredients
- Read the patient information leaflet
- Avoid assuming two differently named products contain different medicines
- Ask a pharmacist if you are unsure
Can You Take OTC Painkillers with Prescription Medicines?
It depends on the prescription medicine and the type of painkiller.
Some prescription medicines can be taken with certain common painkillers, while other combinations may not be appropriate.
For example, NHS guidance for tramadol states that it can be taken with some painkillers such as paracetamol or ibuprofen, but medicines containing codeine should not be added because this can increase side effects.
This is why it is safer to check your specific combination rather than assuming that a familiar painkiller is suitable for everyone.
Be Careful with Combination Cold and Flu Medicines
Cold and flu remedies can contain several active ingredients in one product.
Depending on the product, these may include:
- Pain relief
- Decongestants
- Antihistamines
- Cough medicines
The important thing is to check what is already included before taking another medicine for the same symptoms.
Taking several products without checking their ingredients may result in unnecessary duplication.
Can You Take Antihistamines with Prescription Medicines?
Again, this depends on the antihistamine and the other medicines you take.
NHS guidance for loratadine notes that some medicines can affect how it works or increase side effects. Patients are advised to tell their pharmacist or doctor about other medicines, herbal products, vitamins and supplements they use.
Some medicines can also have similar side effects, such as drowsiness or dry mouth, which may become more noticeable when they are taken together.
Always check the specific antihistamine rather than treating all allergy medicines as interchangeable.
What About Indigestion Medicines?
Some indigestion remedies can affect other medicines.
In some cases, the issue may be the timing of the doses rather than whether the medicines can ever be used together.
For example, NHS guidance for dipyridamole states that certain indigestion medicines may need to be taken several hours apart from some forms of dipyridamole.
This is another reason why a pharmacist may ask exactly which medicine you take rather than simply whether you use “heart medicine” or “indigestion medicine”.
Can Laxatives Affect Prescription Medicines?
Some can.
For example, NHS guidance for Fybogel states that it can change how some medicines work or are absorbed and advises leaving a gap between Fybogel and certain other medicines or supplements.
If you regularly take prescription treatment and need an OTC product for constipation, ask a pharmacist whether the product is appropriate and whether the doses should be separated.
Do Herbal Remedies Count as Medicines?
They should still be mentioned when discussing your medicines.
People sometimes forget to tell healthcare professionals about herbal remedies because they were not prescribed.
However, herbal and complementary products can affect prescription medicines. NHS guidance advises telling healthcare professionals about herbal medicines and warns against stopping prescribed medicine without speaking to a doctor first.
This includes products bought:
- From a pharmacy
- From a health shop
- Online
- From a supermarket
“Natural” does not automatically mean interaction-free.
Vitamins and supplements should also be included when you tell a pharmacist what you take.
Guidance from Guy’s and St Thomas’ NHS Foundation Trust notes that vitamins, supplements and natural or herbal products can affect how prescribed medicines work and recommends checking with a pharmacist before starting something new.
Bring the name or packaging of the supplement if you are unsure exactly what it contains.
What If You Take Several Prescription Medicines?
The more medicines you take, the more important it becomes to keep an accurate medicine list.
Managing several medicines can be complicated, particularly when you also use occasional OTC products, vitamins or supplements.
Useful information to keep includes:
- Medicine names
- Strengths
- Dose
- How often you take them
- Why you take them
- OTC medicines you use regularly
- Vitamins and supplements
- Herbal products
Keeping this information up to date can make it much easier for a pharmacist or another healthcare professional to check your medicines.
What Should You Tell the Pharmacist?
If you want to buy an OTC medicine while taking prescription treatment, tell the pharmacist:
- What prescription medicines you take
- What symptoms you want to treat
- Other OTC medicines you have already taken
- Any medicine allergies
- Herbal remedies or supplements you use
- Any relevant health conditions
If you cannot remember the exact name of a medicine, showing the packaging, prescription list or NHS App medication information may help.
Why Might the Pharmacist Recommend a Different Product?
The product you initially planned to buy may not always be the best option for you.
A pharmacist may recommend something different because:
- Another medicine could interact with it
- You already take a medicine with the same ingredient
- Your existing medicines increase the chance of side effects
- A different treatment may be more appropriate for your symptoms
- Your symptoms may need further assessment
This is one of the reasons some medicines are kept behind the pharmacy counter even though they do not require a prescription.
The NHS explains that pharmacists may ask questions before supplying certain non-prescription medicines to make sure they are suitable.
Should You Stop Your Prescription Medicine to Take an OTC Product?
Do not stop or alter prescription medicines simply because you want to take an OTC treatment.
Some prescription medicines can cause problems if they are stopped suddenly or the dose is changed without professional advice.
General NHS pharmacy guidance recommends checking with a doctor or pharmacist before stopping medicines or changing the dose.
Instead, ask whether there is an OTC option that can be used safely alongside your existing treatment.
What If You Have Recently Started a New Prescription Medicine?
If you have recently started a new medicine, you may still be learning what side effects to expect and how it fits into your routine.
For eligible medicines and conditions, the NHS New Medicine Service allows community pharmacists to provide additional support after a new medicine has been prescribed.
This can be a useful opportunity to discuss:
- Side effects
- How to take the medicine
- Problems remembering doses
- Concerns about other medicines
- Questions about OTC products
Can Your Pharmacist Help with Regular Prescriptions?
Yes. Community pharmacies can provide support with prescription medicines as well as OTC treatments.
If collecting regular medicines is difficult, Biscot Pharmacy also provides a free prescription delivery service for eligible local patients.
What If Your Symptoms Need More Than an OTC Medicine?
Sometimes an OTC product may not be the most appropriate next step.
Depending on your symptoms, a pharmacist may recommend:
- Self-care
- A suitable OTC treatment
- Speaking to your GP
- Another NHS service
- A Pharmacy First consultation for an eligible condition
Biscot Pharmacy also offers the NHS Pharmacy First service for eligible common conditions.
A Simple Checklist Before Taking an OTC Medicine
Before adding an OTC product to prescription treatment, check:
- What is the active ingredient?
- Do any of my other medicines contain the same ingredient?
- Could this product interact with my prescriptions?
- Could it worsen side effects I already experience?
- Do I take vitamins, supplements or herbal products that should be considered?
- Is there anything in my medical history that could affect the choice?
- Have I read the medicine leaflet?
- Am I unsure enough that I should ask the pharmacist first?
Taking a few minutes to check can help avoid preventable medicine problems.
Ask Before Combining Medicines
OTC medicines can be useful for treating everyday symptoms, but they should still be treated as medicines.
The safest approach is to check the exact combination if you already take prescription treatment, particularly when you take several medicines or use supplements and herbal products as well.
A pharmacist can review what you are already taking and help you understand whether an OTC medicine is appropriate.
the prescription app
