Excipients in Tablets: Putting Lactose, Gluten and Colourings in Perspective

Most of a tablet is not active ingredient but excipients: fillers, binders, coatings, colourings. For most people they play no role. For some they do — for example with hereditary fructose intolerance, a wheat allergy or phenylketonuria. And for the most common worry, lactose intolerance, the answer is usually reassuring: the amount of lactose in tablets is, as a rule, far too small to cause symptoms. This guide shows you which excipients really count, what the standard sentences in the package leaflet mean and how to find a suitable product without putting your treatment at risk.

1. What excipients are and why they are there

A tablet containing 5 mg of active ingredient often weighs 100 mg or more. The rest is excipients (listed in the German package leaflet as “sonstige Bestandteile”, other ingredients). They are not filler in the dismissive sense but do real jobs: they make sure that every tablet contains exactly the same amount of active ingredient, that it stays stable, dissolves in the stomach or gut at the right time, is easy to swallow and can be told apart from other tablets.

• Fillers: bring the tablet up to a manageable size — for example lactose, cellulose, starch or mannitol.
• Binders, disintegrants and lubricants: hold the tablet together, make it break down in the body and stop it sticking in the machine — magnesium stearate, for example.
• Coatings and colourings: protect against light and moisture, mask a bitter taste and make tablets distinguishable.
• Preservatives, sweeteners and solvents: mainly in liquid medicines, drops, creams and eye drops.

All the ingredients are listed in the package leaflet — the excipients usually in section 6 (“What the medicine contains”). For certain excipients, the European excipients guideline additionally requires standardised warnings, which appear in section 2.^¹ Important to know: products with the same active ingredient often differ in their excipients. Why the same tablet is on the shelf under different names is explained in the guide Active ingredient vs. brand name.

2. The standard sentences in the package leaflet — and who they affect

The warnings about excipients often sound more dramatic than they are for most people. They are frequently aimed at small, clearly defined groups. The following overview shows the most important ones.^¹

The overview shows the pattern: most warnings are intended for a small group with a specific diagnosis. If you do not have any of the conditions mentioned, you do not, as a rule, need to avoid excipients.

3. Lactose: a realistic assessment

Lactose is one of the most widely used fillers of all — easy to process, stable and neutral in taste. Many people with lactose intolerance get a fright when they read “Lactose-Monohydrat” (lactose monohydrate) in the package leaflet. But the amounts usually tell a different story.

How much is how much?

A tablet usually contains anything from a few to a few hundred milligrams of lactose, often well under 100 mg. For comparison: a glass of milk (200 ml) contains around 9 to 10 grams of lactose. So 100 mg of lactose corresponds to about two millilitres of milk — a sip that barely covers the bottom of a glass.

In its assessment, the European Food Safety Authority (EFSA) concluded that most people with lactose intolerance tolerate up to 12 grams of lactose in one go with no or only minor symptoms.^² Even if you take several lactose-containing tablets a day, you therefore stay far below the amount that usually triggers symptoms.

When lactose can matter after all

• Rare hereditary metabolic disorders: the standard warning in the Summary of Product Characteristics is aimed precisely at this group. In galactosaemia, separate, stricter rules apply, which are set by the treating specialist metabolic clinic.
• Very pronounced lactose intolerance combined with many lactose-containing products — rare, but possible. Here it is worth looking at the total amount.
• Dry powder inhalers: many contain lactose as a carrier. The amount is irrelevant for lactose intolerance — but it does become relevant with a severe cow's milk protein allergy (see below).

More about the condition itself, the breath test and hidden lactose in food is explained in the article Lactose intolerance.

4. Gluten: what people with coeliac disease should know

Gluten can get into a tablet via just one excipient: wheat starch. Other starches — maize, potato or rice starch — are gluten-free. Most tablets do not contain wheat starch anyway.

When they do, it is highly purified for use in medicines. The package leaflet then contains a standard sentence: the medicine contains only very low levels of gluten, is regarded as “gluten-free” and is very unlikely to cause problems if you have coeliac disease; the maximum amount of gluten per tablet is also stated in micrograms.^¹ To put this in context: in the EU, foods may be labelled gluten-free if they contain no more than 20 mg of gluten per kilogram. Medicines are therefore only rarely a relevant source of gluten; advice specifically for people with coeliac disease is provided by the German Coeliac Society (DZG).^³

• A wheat allergy is something different — here the immune system reacts to wheat proteins. According to the standard warning, you should then not take products containing wheat starch.
• Only “starch”, with no source given? Ask at the pharmacy where it comes from — they can check this with the manufacturer.
• Check food supplements and herbal products sold as foods separately — they are subject to food law, where gluten has to be labelled as an allergen.

How to manage a gluten-free diet in everyday life and which check-ups make sense is covered in the article Coeliac disease.

5. Colourings: E numbers without panic

Colourings in tablets are not just cosmetic. They protect light-sensitive active ingredients, make different strengths distinguishable and help to prevent tablets being mixed up. Most people tolerate them without any problems.

Azo dyes

A group of synthetic colourings — including tartrazine (E 102), sunset yellow FCF (E 110), azorubine (E 122), ponceau 4R (E 124) and brilliant black BN (E 151) — carries the standard warning that they may cause allergic reactions. What is usually meant are intolerance reactions such as weals or, less often, breathing difficulties. People with chronic hives or a painkiller intolerance are considered particularly sensitive. However, the evidence on this is limited, and many of those affected tolerate the small amounts in tablets.

Mineral pigments and titanium dioxide

Iron oxides (E 172) and titanium dioxide (E 171) are the most common colouring agents in tablet coatings and practically never cause intolerances. Titanium dioxide has no longer been authorised in food in the EU since 2022, because a risk to genetic material could not be ruled out. It is currently still used in medicines because replacing it is technically complex; the question continues to be reviewed at European level. This does not mean any acute risk for you — and it is not a reason to stop a treatment you need.

6. Other excipients with real consequences

Some excipients really are important for certain groups — in some cases more important than lactose or gluten.

Sorbitol and fructose

In the very rare hereditary fructose intolerance (an inherited disorder of fructose metabolism), fructose, sorbitol and sucrose can trigger severe hypoglycaemia and liver damage. People affected must strictly avoid these substances in medicines too. This should be distinguished from the common fructose malabsorption in the gut: here, small amounts in tablets usually do not matter. Larger amounts of sorbitol, for example in liquid medicines, can, however, cause bloating and diarrhoea in anyone.

Aspartame

This sweetener is found mainly in effervescent and chewable tablets and in liquid medicines. It is a source of phenylalanine and is therefore relevant in phenylketonuria (PKU).

Sodium in effervescent tablets

Effervescent tablets contain sodium salts for the fizzing effect — often several hundred milligrams of sodium per tablet. If you are supposed to restrict salt because of heart failure, high blood pressure or kidney disease and take several effervescent tablets a day, you should ask about a different dosage form.

Alcohol in drops and liquid medicines

Some drops, herbal tinctures and liquid medicines contain ethanol as a solvent. For adults, the amounts are usually small; they become relevant in children, in pregnancy, in alcohol use disorder and with active ingredients that interact with alcohol. More on this in the guide Medications and alcohol.

Preservatives and rare allergens

Parabens in creams and liquid medicines can trigger contact allergies. Benzalkonium chloride in eye drops irritates the surface of the eye with long-term use; for many eye drops, preservative-free single-dose units are available. Allergies to polyethylene glycol (macrogol) and related substances are very rare but documented — anyone with an allergy like this should be under the care of an allergy specialist and have it noted in every plan.

7. Step by step: how to find a suitable product

If an excipient really is relevant for you, there is almost always a solution — usually a product with the same active ingredient and a different formulation. Here is how to go about it:

1. Clarify the diagnosis. Lactose intolerance, milk protein allergy, coeliac disease, wheat allergy, hereditary fructose intolerance — these are different things with different consequences. A confirmed diagnosis stops you avoiding more than you need to.
2. Note it in your medication plan. The nationwide standard medication plan has its own field for allergies and intolerances.^⁴ Enter exactly what you do not tolerate — as specifically as possible.
3. Mention it with every prescription. The practice software often shows only the active ingredient, not the excipients of the product that is dispensed. One sentence is enough: “I have a wheat allergy.”
4. Let the pharmacy do the searching. Pharmacies can use their databases to compare the excipients of different products with the same active ingredient and pick out a suitable one.
5. Know how discount contracts work. If the product that your health insurer specifies under its discount contract (Rabattvertrag) is unsuitable for you because of an excipient, the pharmacy can dispense a different one by citing pharmaceutical concerns (pharmazeutische Bedenken).^⁵ If a specific product is needed long term, the practice can rule out substitution on the prescription (by marking the aut idem box).
6. Check the package leaflet with every new pack. Manufacturers occasionally change their formulations. A quick look at sections 2 and 6 is enough.
7. Document and report reactions. Note the product, the reaction and when it happened. You can also report suspected side effects yourself to the BfArM (German Federal Institute for Drugs and Medical Devices).^⁶

8. Excipient, active ingredient or side effect? Telling them apart

If you react to a new medicine, you often suspect an excipient first. In fact, other causes are usually behind it:

• Side effect of the active ingredient: the most common explanation — for example gastrointestinal symptoms, headache or dizziness. These usually occur regardless of the product.
• Allergy to the active ingredient: a skin rash, weals or swelling after antibiotics or painkillers are usually due to the active ingredient.
• Reaction to an excipient: possible, but comparatively rare. One clue is when the symptoms occur only with one particular product and not with another containing the same active ingredient.

9. Special groups

• Children: liquid medicines more often contain sugar, sorbitol, flavourings, colourings and sometimes alcohol. For many active ingredients, sugar-free or alcohol-free versions are available. More in the guide Medications for children.
• Pregnant women: watch out for drops and tinctures containing alcohol, and ask whether there are alternatives.
• Older people and people with heart or kidney disease: sodium in effervescent tablets adds up — especially if several effervescent products are taken every day.
• People with diabetes: sugar in tablets is usually negligible, but in liquid medicines and lozenges it can become significant if they are taken often.
• People with congenital metabolic disorders (PKU, hereditary fructose intolerance, galactosaemia): every new product should be checked before the first dose — ideally in consultation with the specialist metabolic clinic.

10. How brite helps you with excipients and intolerances

Your intolerances always with you — with brite

Allergies recorded in your plan, product switches documented, interactions checked. Free of charge.

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