How can I check drug interactions at home?

The fastest way is to use an app with an interaction database. mojApteczka automatically checks interactions between all medicines in your home medicine cabinet using the DDInter 2.0 database, which contains more than 1.3 million interaction pairs.

Can over-the-counter medicines be dangerous?

Yes. Too much paracetamol can damage the liver, ibuprofen can raise blood pressure, and first-generation antihistamines can cause drowsiness. OTC medicines can also interact with prescription-only medicines.

Which medicines are dangerous for children?

Aspirin (risk of Reye's syndrome), codeine, loperamide, and many adult cough medicines. Always check the age restrictions on the packaging and in the patient information leaflet.

Can I take medicines during pregnancy?

Paracetamol is generally considered safe during pregnancy. Avoid ibuprofen (especially in the third trimester), aspirin in pain-relief doses, and retinoids. Always consult your doctor.

What is polypharmacy?

Polypharmacy means taking 5 or more medicines at the same time. It mainly affects older adults and increases the risk of interactions, side effects, and dosage errors.

Medicine Safety at Home — Everything You Need to Know

A complete guide to medicine safety at home. Drug interactions, children's dosage, pregnancy, older adults, over-the-counter medicines, and safe storage.

Medicines are meant to help. That is their only job. The problem is that a medicine used incorrectly can cause harm — sometimes more harm than the illness it was meant to treat. And we are not talking about dramatic mistakes from disaster films. We are talking about everyday situations: a headache tablet washed down with grapefruit juice, an adult syrup given to a child, or two medicines taken together that work well separately but put extra strain on the liver when combined.

Most medicine-related incidents at home are not caused by neglect. They happen because the right information is not available at the right moment. This guide brings together everything you need to know about medicine safety at home — from interactions, dosage for children and older adults, to storage and medicines you may be keeping even though you should not.

Why Medicine Safety Is Everyone’s Business

The statistics are clear. In Poland, thousands of hospitalisations each year are caused by adverse drug reactions — and a significant share of them could have been avoided if the patient had known about an interaction, the correct dose, or improper storage.

You do not need to be a pharmacist to keep your family safer around medicines. You need to know a few fundamental rules and have tools that help you apply them.

Drug Interactions — The Hidden Risk in Your Cabinet

Drug interactions happen when two or more medicines affect one another — strengthening, weakening, or changing their effects. They can be dangerous, and they are hard to spot because each medicine may appear to work correctly on its own.

The Most Common Types of Interactions in a Home Medicine Cabinet

Medicine + medicine. A classic example is ibuprofen and aspirin. Both are non-steroidal anti-inflammatory drugs (NSAIDs). Taken together, they increase the risk of gastrointestinal bleeding. Another example is paracetamol and a cold medicine — many combination cold remedies contain paracetamol, so it is easy to take a double dose without realising it.

Medicine + food. Grapefruit inhibits the CYP3A4 enzyme in the liver, which metabolises many medicines — from statins, through blood pressure medicines, to immunosuppressants. The effect? The medicine stays in the body longer and works more strongly than it should. Dairy products, in turn, bind tetracycline antibiotics and reduce their absorption.

Medicine + supplement. St John’s wort (Hypericum) interacts with hormonal contraception, antidepressants, and immunosuppressants. Iron reduces the absorption of levothyroxine. High doses of vitamin K can change the effect of warfarin.

How to Check Interactions

You do not need to remember every possible interaction. You need a tool that can check them for you. In mojApteczka, the interaction checker analyses your inventory and alerts you when two medicines in your home medicine cabinet may react dangerously with one another.

You can find a detailed guide to checking interactions yourself, and what to pay attention to, in How to Check Drug Interactions at Home.

Medicines and Children — A Separate World of Dosage

A child is not a small adult. A child’s metabolism processes medicines differently — with different proportions of water in the body, different liver capacity, and different receptor sensitivity. That is why paediatric dosage is not “half an adult tablet”, but a separate field in its own right.

Medicines That Can Harm a Child

Some medicines in your home medicine cabinet that are safe for adults are dangerous for children:

Aspirin — risk of Reye’s syndrome in children under 12.
Medicines containing codeine — banned in children under 12 since 2015 (EMA decision) because of the risk of severe respiratory depression in ultra-rapid metabolisers.
Loperamide (e.g. Imodium) — not for children under 6.
Oxymetazoline nasal drops — the adult version has too high a concentration for children.

Safe Dosage Rules

Dose by body weight, not only by age. Use the measuring spoon or syringe provided, not a kitchen teaspoon. Never split an adult tablet in half as a substitute for a paediatric medicine. Write down what you gave and when — at three in the morning, you may not remember whether you gave the medicine one hour or two hours ago.

In mojApteczka, paediatric classification marks each medicine in your cabinet as safe for children, for adults only, or veterinary — so you do not have to search through the patient information leaflet at two in the morning.

We cover the full topic in detail in Medicines for Children — Safety and Dosage.

Medicines During Pregnancy — Caution Is Not Enough

Pregnancy is a time when most medicines need to be reassessed. Even those you have taken safely for years may affect foetal development — especially in the first trimester, when organs are forming.

Safety Categories

Not all medicines are equally risky. Paracetamol is generally considered safe during pregnancy. Ibuprofen is not, especially in the third trimester. Antibiotics? It depends on the group. Blood pressure medicines? Some are permitted, while others are strictly contraindicated.

Rule Number One

Do not stop taking prescription-only medicines on your own, but do not take anything new without consulting a doctor or pharmacist. This also applies to supplements, herbal products, and OTC medicines.

You can find a full guide to medicine safety during pregnancy — with specific examples of what can be used and what should be avoided — in Medicines and Pregnancy — What Is Safe?.

Polypharmacy — When There Are Too Many Medicines

Polypharmacy means taking five or more medicines at the same time. It mainly affects older adults, but not only them — anyone with a chronic condition, allergies, and supplements can drift into this area without noticing.

Why Is It Dangerous?

The more medicines there are, the greater the risk of interactions. But interactions are not the only issue. Polypharmacy also means:

A prescribing cascade — a side effect of one medicine is treated with another medicine, which has its own side effects, which are then treated with another medicine.
Adherence problems — the more tablets there are, the easier it is to miss a dose or make a mistake.
Organ strain — the liver and kidneys have limited capacity to metabolise medicines. With a large number of products, that capacity can be exceeded.

What Can a Caregiver Do?

Keeping an up-to-date list of all medicines is the absolute minimum. If you care for an older parent or grandparent who takes many medicines, this list should be available to the doctor, pharmacist, and anyone who needs to know what that person is taking in an emergency.

Read more about managing many medicines in older adults in Polypharmacy — Managing Multiple Medications for an Older Adult.

OTC Medicines — Does “Over-the-Counter” Mean “Safe”?

This is one of the most common misunderstandings. Over-the-counter medicines have gone through a rigorous authorisation process and are safe — provided you use them according to the patient information leaflet. In practice, that does not always happen.

Common OTC Traps

Double dosing with paracetamol. You take paracetamol for a headache and, at the same time, a cold medicine that contains it. The total dose exceeds the safe limit, and you may not even know it.

Combining NSAIDs. Ibuprofen plus aspirin, ibuprofen plus naproxen — these medicines should not be used together, yet many people do so without realising they all belong to the same group.

Long-term use. An OTC medicine intended for short-term use (for example, proton pump inhibitors for heartburn) can cause serious side effects if taken for months.

We cover the full topic in Over-the-Counter Medicines — Does OTC Mean Safe?.

Storage — Mistakes Almost Everyone Makes

Medicine safety starts with storage. A medicine stored in the wrong conditions loses effectiveness, changes its chemical properties, and in extreme cases may become toxic.

Three Serious Mistakes

Keeping the home medicine cabinet in the bathroom. Humidity and temperature changes degrade medicines faster than almost anything else.
Keeping medicines on a windowsill. Direct sunlight breaks down many active ingredients.
Keeping medicines without packaging. A blister removed from its box and thrown into a drawer loses traceability — you no longer know what medicine it is, what dose it contains, or what its expiry date is.

Which specific medicines in your home medicine cabinet are you probably storing incorrectly? Find the answer in 10 Medicines You Store Wrong.

Medicine Substitutes — A Cheaper Alternative, but Not Always Identical

When the original medicine is expensive or unavailable, a pharmacist may suggest a substitute — a generic medicine with the same active ingredient in the same dose. In the vast majority of cases, substitutes work just as effectively.

But not always. Differences in excipients can affect absorption speed, gastric tolerance, or trigger allergic reactions in people who are sensitive to specific fillers. With some medicines (for example, thyroid medicines and anti-epileptic medicines), switching substitutes requires particular caution.

We explain how to find a cheaper equivalent safely, and what to watch out for, in Medicine Substitutes — How to Find a Cheaper Alternative.

Veterinary Medicines in the Home Medicine Cabinet

If you have animals, you probably also have veterinary medicines at home. And they are probably kept in the same cabinet as human medicines. This creates a risk of mix-ups that is not theoretical — it happens more often than you might think.

Veterinary medicines have different dosages, different excipients, and sometimes different active ingredients from human medicines. Giving a veterinary medicine to a person — or the other way round, giving a human medicine to an animal — can have serious consequences.

We explain how to separate veterinary medicines, how to label them, and what must never be mixed in Veterinary Medicines in the Home Medicine Cabinet.

Digital Tools for Medicine Safety

Knowledge is one thing. Tools that help you use it every day are another. Checking interactions manually, remembering doses, keeping an eye on expiry dates — these are tasks a computer does better than a person.

Interaction Checking

The drug interactions feature in mojApteczka analyses your inventory and flags potential conflicts. It does not replace a pharmacist, but it gives you an early warning — before you take two medicines that should not be combined.

Paediatric Classification

Paediatric classification marks each medicine as safe for children, for adults only, or veterinary. At two in the morning, when you are looking for medicine for a feverish child, that information is invaluable.

Alerts and Notifications

An expired medicine is an unsafe medicine. Automatic alerts about upcoming expiry dates are the simplest way to avoid using a medicine after its date has passed.

Safety Is a Habit, Not a One-Off Task

You cannot tidy the home medicine cabinet once and consider the topic closed. Medicine safety at home is an ongoing process — new medicines appear in the cabinet, old ones expire, children grow and their needs change, and older adults receive new prescriptions.

The good news: when you have a system — whether analogue (a medicine list on the cabinet door) or digital (an app that does it for you) — keeping things safe takes a few minutes a month, not hours.

Start with one thing: review your home medicine cabinet for safety today. Check whether you are combining medicines that should not be taken together. Check whether children’s medicines are separated from adult medicines. It is 15 minutes that may protect your family from a serious problem. The Android app is also available on Google Play.