The Difference Between Cialis & Tadalafil

Tadalafil and Cialis are the same medication. Tadalafil is the active ingredient in Cialis, and since Eli Lilly’s original patent expired in 2017, it has also been available as a generic drug under the name Tadalafil. 

Both contain an identical active ingredient at identical doses, and clinical trials show they produce identical results. 

The only meaningful difference is price. Generic tadalafil can cost up to three times less than branded Cialis. We explain the science behind why they’re equivalent, what the dosage options are, and how to choose between them. 

How it works

How do Cialis and tadalafil work? 

Both work by blocking an enzyme called phosphodiesterase type 5 (PDE5). This enzyme restricts blood flow to the penis. By blocking the enzyme, tadalafil allows the blood vessels in the penis to relax and widen, making it easier to get and maintain an erection when you’re sexually aroused.  

The medication does not cause an erection on its own, sexual stimulation is still needed. 

Neither tadalafil nor Cialis affects your sex drive, and neither works for premature ejaculation or other sexual difficulties. They only help with getting an erection. 

In clinical trials, tadalafil was effective in approximately 81% of men across a wide range of ED causes and severities. 

Why generics are legally required to be equivalent 

The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) requires all generic medicines to demonstrate bioequivalence to their branded counterpart before they can be approved. 

Bioequivalence means that the generic and original version of the drug are absorbed by your body and used at the same rate and to the same extent, so they treat your condition just as well.  

For Tadalafil, this means generic manufacturers must prove that the drug behaves identically to Cialis before it can be sold. 

The only differences between branded Cialis and generic tadalafil are cosmetic such as: 

• the shape  

• colour 

• packaging of the tablet 

The active ingredient tadalafil is chemically identical. Any inactive ingredients such as fillers or coatings may differ slightly between manufacturers, but these have no effect on how the drug works or its safety profile. 

When you take generic tadalafil, your body cannot tell the difference between it and branded Cialis, so you’re getting the same treatment at a lower price. 

Efficacy and Usage 

Erectile dysfunction is far more common than many men realise. A 2022 real-world study of over 12,000 UK men found that 41.5% reported some degree of ED. It becomes more common with age, but it affects men of all ages and it is treatable. 

In clinical trials, tadalafil was found to be effective in approximately 81% of men with ED across a wide range of causes and severities, including men with diabetes, cardiovascular disease, and after prostate surgery.  

Price Comparison Table 

How much cheaper is generic tadalafil than Cialis? 

Generic tadalafil typically costs two to three times less than branded Cialis for the same dose and quantity.  

The price difference exists because Eli Lilly, who manufacture Cialis set and control the price without competition from the sale of the generic. Once the patent expired in 2017, multiple manufacturers began producing tadalafil, significantly driving down the cost. 

Both the generic and branded versions require a prescription. At The Family Chemist, you can complete a free online consultation to check your eligibility and get a clinician to review. 

Side effects of tadalafil and Cialis 

Because tadalafil and Cialis contain the same active ingredient, they have identical side effects. Most men tolerate tadalafil well, and many experience no side effects at all. When side effects do occur, they are usually mild and short-lived. 

Common side effects (affecting up to 1 in 10 men): 

• Headache 

• Indigestion or stomach discomfort 

• Back pain or muscle aches 

• Flushing (redness or warmth in the face) 

• Stuffy or runny nose 

• Dizziness 

Less common but important side effects to know about: 

• Sudden loss of vision or hearing — stop taking tadalafil and seek urgent medical attention 

• Priapism (an erection lasting more than 4 hours) — this is a medical emergency requiring immediate treatment 

• Low blood pressure, particularly if taken with nitrates or certain other medications 

If you experience any side effects that concern you, contact your prescriber or the NHS 111 helpline. 

Who should not take tadalafil?

Tadalafil is not suitable for everyone. You should not take it if you take nitrate-based medicines for chest pain or heart conditions (such as glyceryl trinitrate or isosorbide mononitrate), as the combination can cause a severe and dangerous drop in blood pressure. 

Tell your prescriber about all medications you take before starting tadalafil, especially: 

• Nitrates (e.g. GTN spray, nicorandil) – this combination is contraindicated 

• Alpha-blockers (used for high blood pressure or prostate conditions) – can increase the risk of low blood pressure 

• Other ED medications – do not take more than one PDE5 inhibitor at a time 

• HIV medications, antifungals, or antibiotics – some can increase tadalafil levels in the blood 

Alcohol: Drinking significant amounts of alcohol while taking tadalafil can increase the risk of side effects including dizziness and low blood pressure. 

The Family Chemist online consultation will screen for any contraindications before issuing a prescription, ensuring tadalafil is safe for you to take. 

Tadalafil for an enlarged prostate (BPH)

Tadalafil (at a daily dose of 5 mg) is the only PDE5 inhibitor licensed to treat both erectile dysfunction and the symptoms of benign prostatic hyperplasia (BPH) — also known as an enlarged prostate. BPH causes urinary symptoms including difficulty starting urination, a weak urine flow, and needing to urinate frequently or urgently.  

In clinical trials, once-daily tadalafil 5 mg significantly improved urinary symptoms in men with BPH, and simultaneously improved erectile function in those who also had ED. This makes it a particularly useful treatment option for men who have both conditions — which is common, as the two often occur together in men over 50.  

Branded Cialis and generic tadalafil are equally effective for BPH treatment. As with ED, the active ingredient is identical. If you are being treated for BPH as well as ED, speak to your prescriber about whether a daily dose of 5 mg is right for you. 

Tadalafil vs sildenafil: which should I choose? 

The main practical difference between tadalafil (Cialis) and sildenafil (Viagra) is how long they last. Tadalafil remains active for up to 36 hours, whereas sildenafil typically lasts 4–6 hours.  

In a crossover trial comparing both drugs in men with ED, 71% chose to continue with tadalafil over sildenafil after trying both mainly because the effect lasted longer.