Cialis’ trademark yellow almond-shaped tablets are formulated from the active ingredient Tadalafil and a host of inactive ingredients involved in forming a soluble pill. Below are all the ingredients listed on a pack of Cialis, and what each substance’s role is in the medication.


Tadalafil is the drug, or active ingredient, within the medication branded as Cialis. It is known as a PDE5-inhibiting drug, which allows for the vasodilation of blood vessels in specific areas of the body when taken.

Cialis is the form of Tadalafil prescribed for patients with erectile dysfunction. Cialis is prescribed containing varying dosages of Tadalafil: 2.5mg, 5mg, 10mg and 20mg. The 2.5mg and 5mg Tadalafil doses are for daily use of the drug, while the stronger 10mg and 20mg variants are reserved for patients who wish to take the drug infrequently, as and when they require it.


Croscarmellose Sodium

This inactive substance acts as a common emulsifier in pharmaceutical products and can help to deliver the drug to the target location within the body. It is a distintegrant – an ingredient that helps the tablet dissolve properly in the body – meaning that the active ingredient is properly released and absorbed. Without a disintegrant, the tablet may not sufficiently dissolve and therefore the effectivity of the drug is not optimal.

Hydroxypropyl Cellulose

Hydroxypropyl cellulose (or HPMC) is a coating agent involved in the film-coating of tablets. Generally, tablets are film-coated to either prevent the tablet from dissolving in the stomach and upsetting the stomach, putting off dissolution to the intestines or further in the digestive tract; or to protect the medication from being destroyed by stomach acid before it can reach the intestines where it is absorbed.

Iron Oxide

Commonly used as a food colouring with the E number E172, iron oxide can range in colour from yellow to red to black, and every colour in between. It is used to achieve Cialis’ yellow colouring – ranging in intensity as the tablets’ dosages increase. Besides food colouring, metallic rust is a form of iron oxide, and the compound is found in haemoglobin.

Lactose Monohydrate

Lactose monohydrate is a form of natural sugar found in milk, which can be extracted for many different uses. It is used in the pharmaceutical industry as an inexpensive compressor in the formation of tablets: basically, it helps to hold everything together.

Patients who are allergic to lactose should be cautious when taking medications that contain it. Even though it is included in microscopic doses, even that is enough to cause an allergic reaction in some people. Always inform your doctor if you have any allergy before taking a new medication.

Magnesium Stearate

This inactive ingredient is commonly used in pharmaceutical products and nutritional supplements as an effective flow agent. What this means is that it prevents drug ingredients from sticking to manufacturing equipment, ensuring that the quantities of each ingredient remain the same in each tablet produced. If some substances are left as residue on equipment, the tablet will lack some active ingredient, therefore the dose of active ingredient in that tablet will be diminished. Without using a flow agent, dosages will be inconsistent across the batch.

Microcrystalline Cellulose

This is a form of refined wood pulp, which is commonly used as an excipient by the pharmaceutical industry. It is also a compressor, holding tablet ingredients together and helping to form a solid tablet.

Sodium Lauryl Sulphate

This is another excipient ingredient, involved in the dissolution and release of active ingredients after consumption of tablets.


Talc, or talcum, is a silicate mineral used as an anti-caking agent in pharmaceuticals, for improved tablet compression and powder flow. It is an absorbent and can aid in the manufacture of extended-release formula drugs.

Titanium Dioxide

This is used as a white pigment or a coating for tablets. It is not absorbed by the digestive system and is classified safe to consume in small doses like those found in tablets by the EFSA (the European Food Safety Authority).