Cialis

Cialis (Tadalafil) Specs

Cialis is a licensed ED treatment that stays active in your system for up to 36 hours. During this window, you’ll get multiple “uses” (erections) out of one Cialis pill. It’s the longest working ED treatment available on the US market.

How does Cialis work? The active ingredient in Cialis is tadalafil, which helps blood vessels in the penis dilate, increasing blood flow. Tadalafil has been clinically proven to help over 81% of men with ED achieve easier, more reliable and longer-lasting erections.

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Medically reviewed by

Mr Craig Marsh

Clinical Reviewer

on Sep 17, 2024.

Meet Craig

Last updated on Sep 19, 2025.

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What is Cialis (tadalafil)?

Cialis is made by the pharmaceutical company Lilly. Available in 2.5mg, 5mg, 10mg, and 20mg doses, it was approved in the US in 2003. By the end of that year, Cialis was named one of TIME Magazine’s “Coolest Inventions.”

There are two versions of Cialis: Cialis and Cialis Daily. Cialis contains 10mg or 20mg of the active ingredient tadalafil. The effects of Cialis will last up to 36 hours. Other ED pills stay active in the body for 4-5 hours. This offers huge flexibility between when you pop the pill and when you hit the bedroom. Cialis daily, taken every day, has a lower dose of 2.5mg or 5mg of tadalafil. Cialis Daily is always at work in your system meaning you’re ready to go any time, any day.

The generic name for Cialis is Tadalafil. Generic versions are normally named after the treatment’s active ingredient. Cialis is the branded medication, Tadalafil is an unbranded version made by pharmaceutical companies other than Lilly. Generic medications are regulated to work as effectively as their branded counterparts: both Cialis and generic Tadalafil are equally as good at treating ED.

How does Cialis work?

When aroused, the blood vessels in your penis dilate. Blood is sent into shaft-like columns in the penis, and you get hard. If you have erectile dysfunction (ED), blood vessels at the base of the penis are too tight to let blood through. The result is difficulty getting hard or hard enough for sex.

What does Cialis do? Tadalafil, the active ingredient in Cialis, is a PDE5 inhibitor. PDE5 is the enzyme that causes blood vessels to tighten. By limiting how active PDE5 is, blood can flow into the penis and you get an erection.

Because tadalafil causes blood vessels to open more widely, Cialis lowers blood pressure. The effect is temporary and shouldn’t cause any health issues. PDE5 inhibitors only work in the presence of nitric oxide, which is released during sexual arousal, so you will need to be aroused for Cialis to work.

How is Cialis Daily different?

Cialis for daily use is a good choice if you have sex three or more times a week. It may be a better option if you’re in a long-term relationship and want to be “ready to go” at any moment. There are two options for Cialis Daily: 2.5mg of tadalafil, which is the normal starting dose, and a 5mg version if you don’t see the results you’re looking for.

If you have sex on a less regular basis, or your ED comes and goes, Cialis may be a better option. The key difference is the dosing strategy. On-demand Cialis provides a high dose that lasts up to 36 hours. Cialis Daily uses a lower daily dose to build and maintain a constant level of the medication in your body, allowing you to be ready for sex at any time.

You can read more information on the different Tadalafil doses available here.

What does Cialis look like?

Cialis is an orange-yellow, film-coated tablet in the shape of an almond. Each Cialis tablet is marked on one side with the dose of tadalafil it contains. For example, a Cialis pill with 2.5mg of tadalafil will be marked “C 2 ½” and one with 10mg will be marked “C 10.”

Do Tadalafil pills look different to Cialis?

Generic Taladafil is available in a variety of shapes and colors as it is produced by several different labs. What will be the same for all unbranded Tadalafil pills is that they should each be equally as effective at treating ED.

How to take Cialis

When taking Cialis, swallow one tablet whole with water, never split tablets or double up on your dosage. Cialis should be taken at least 30 minutes before sex with or without food.

Don’t take more than one dose of Cialis in a 24-hour period. How to take tadalafil will be the same as how you use Cialis.

Whichever Cialis dosage you’re taking, you should always follow the instructions and read the patient information leaflet beforehand. If you take your medication as you should and you’re still not getting the desired effect then you may need to look into a dosage change.

How to get the maximum effect from Cialis

Treat getting an erection like you would as though you didn’t have ED. Whether it be visual sexual stimulation or tactile foreplay, you will only get an erection when taking Cialis if you’re also sexually aroused.

If your prescription is for Cialis Daily, it can help to take it at the same time each day to maintain a steady level of tadalafil in your body. Some options for how to make Cialis work better include following a healthy lifestyle and limiting smoking, heavy drinking and stress, which can all worsen the symptoms of ED.

Cialis and alcohol at the same time: can I or can’t I?

You should use alcohol with caution when taking Cialis. While small amounts aren’t likely to cause problems, both Cialis and larger amounts of alcohol can lower your blood pressure. As a result, excessive drinking (a blood alcohol level over 0.08%) may cause dizziness and is best avoided.

Cialis with food

Cialis can be taken with or without food. Unlike some other ED medications, its effectiveness isn’t impacted by what you eat, so you don’t need to worry about avoiding heavy or high-fat meals before taking your dose.

Grapefruit juice can increase the metabolism of PDE5 inhibitors in the body. This means a greater risk of side effects, so avoid grapefruit juice when taking Cialis.

How long does Cialis take to work?

Cialis should begin to work in 30-60 minutes. If you want to be able to guarantee that you’ll be ready to go, the best time to take Cialis is around 2 hours before sex, to ensure it’s active in your body.

A few things can impact how long it takes Cialis to work including other health conditions, other medications you take, your age, your diet and your dose.

While regular Cialis may take a moment to kick in, Cialis Daily is taken every day, so it remains active in the body around the clock. One of the reasons that Cialis has high patient satisfaction ratings: you’re ready to go at any time of the day, no wait necessary.

How long does Cialis last?

The Cialis effective time — how long it will aid you in getting an erection — is 24 to 36 hours. If you’re wondering “how long does tadalafil last?” The answer is the same: 24 to 36 hours.

This doesn’t mean you’ll have an erection for 36 hours, which would be dangerous. (If you get an erection that lasts over 4 hours you should go to the hospital.) What it means is that for a 36-hour window after you pop that pill you should find it easier to get a strong, hard erection which can be used during sex.

How often can you take Cialis?

Cialis can be taken every 24 hours, but remember that Cialis is effective for up to 36 hours. The drug’s half-life (the time it takes for its concentration to halve in your body) is about 17.5 hours, which explains why its effects are so long-lasting.

If you’re finding that the 36-hour window isn’t offering you enough leeway and you’re tending to take a second pill soon the next day, speak with your clinician. They may decide that Cialis Daily is a better option for you.

How many years can you take Cialis for?

Current research suggests Cialis is safe to take for several years.

A clinical trial with more than 1,000 men using tadalafil for up to 24 months found that only a minority (8.6%) experienced side effects with long term use, but none were consistently associated with tadalafil use. The most common side effects reported were headache, dyspepsia, nasopharyngitis, and back pain. Overall, the study concluded tadalafil was well-tolerated for long term use.

At present, studies show that Cialis is safe for a couple of years, but there’s limited research on time spans greater than this (like decades).

Does Cialis lose effectiveness over time? No, Cialis does not lose potency over time. If you find Cialis stops working it may be that the underlying factors contributing to your ED may have worsened. Talk to your doctor if you find this is the case, they may decide a higher dose is the answer or look to alternative therapies.

How well does Cialis work?

Cialis is an effective treatment for mild to severe ED. On the standard starting dose of 10mg of the active ingredient in Cialis, tadalafil, 71% of men reported an erection suitable for sex.

On a higher 20mg dose of tadalafil, 73% of men reported improved erections. On Cialis Daily, 84% of men reported improved erections and 72% preferred Cialis Daily over on-demand.

In a study of over 2000 men with ED who were given either a 20mg or 10mg dose of tadalafil, 84% reported improved erections and 68% successfully got an erection and followed it with sex.

The percentage of men who responded that they were satisfied with their ability to get an erection after treatment with tadalafil ranged from 72% to 91%.

Does Cialis make you bigger?

No, Cialis doesn’t increase the size of your penis. However, if you weren’t able to become fully erect before taking Cialis, it might seem larger as you’re able to get full erections.

Does Cialis have other uses?

Cialis (tadalafil) can also be used to treat benign prostatic hypertrophy (BPH), commonly known as an enlarged prostate.

BPH affects up to 50% of men in their 60s and 90% of men in their 80s. Symptoms include difficulty urinating, a weak urine stream and frequent urination at night.

Is Cialis safe?

Yes, there is no evidence to suggest that Cialis is unsafe and most men who take Cialis (Tadalafil) won’t experience serious side effects. Cialis and Tadalafil are also prescription-only medicines. Meaning if your doctor has prescribed them, they’ve judged that the benefits outweigh the risk of side effects.

That said, it’s important to read the leaflet which comes with your medication. Cialis side effects can happen and the drug can interact with other medications causing side effects such as headache, stomach upset, muscle pain, stuffy nose, flushing or dizziness.

Is Cialis for men only?

Yes. There is no Cialis for women; only men should take it and its generic (unbranded) version, Tadalafil.

While ED pills are not for women, treatments for low sexual desire (HSDD) do exist. Medications like Flibanserin (Addyi) and Bremelanotide (Vyleesi) are FDA-approved in the US for this purpose.

Does Cialis expire?

Yes, check the packaging your medication came in for the manufacturer expiration date.

While Cialis (Tadalafil) pills shouldn’t be harmful after the expiration date and they don’t “go bad,” they’re unlikely to work as well. The expiration date for any given drug will be how long the manufacturer is willing to guarantee that the product meets the labelled standards.

This page was medically reviewed by Mr Craig Marsh, Clinical Reviewer on Sep 17, 2024. Next review due on Sep 17, 2027.