You can take Cialis as needed or once daily, depending on the dose and how it’s prescribed. Your dosage, overall health, and lifestyle can affect how well the medication works. Taking the medication properly will help you get the maximum effect.

Cialis is a brand of tadalafil, one of the most popular medications to treat erectile dysfunction (ED). It was first approved in 2003.

Tadalafil is available in tablet form:

  • 2.5 milligrams (mg)
  • 5 mg
  • 10 mg
  • 20 mg

Depending on the dose for ED, you can use it as needed before sexual activity or take it once a day.

A 2017 review of 16 studies comparing tadalafil and sildenafil (Viagra) found they’re equally effective for ED and have similar safety profiles.

However, the review found that tadalafil is preferred over sildenafil by users and their partners and increases confidence.

Cialis is a phosphodiesterase type 5 (PDE5) inhibitor. It works for ED by relaxing smooth muscle in the blood vessels of the penis, therefore increasing blood flow.

PDE5 inhibitor medications work in 60–70% of people with ED. Tadalafil is the longest-lasting PDE5 inhibitor medication for ED.

As-needed dosing

The usual starting dose for as-needed Cialis is 10 mg. It’s adjusted upward or downward depending on how you react to the medication.

Don’t take more than one dose per day to avoid the risk of a prolonged, painful erection (priapism), drop in blood pressure, or other serious side effects.

Take one tablet 30 minutes before sexual activity as directed by your doctor.

Daily dosing

The usual starting dose for once-daily Cialis is 2.5 mg. Your doctor might increase the dose to 5 mg based on your reaction to the medication.

Take one tablet as prescribed at the same time each day. Many people who take Cialis prefer this dosing because it provides flexibility for the timing of sexual activity.

Cialis doesn’t work right away.

For an as-needed dose, plan to take Cialis at least 30 minutes before sexual activity, but bear in mind it may take as long as 2 hours to take effect.

Cialis requires sexual stimulation to be effective, so arousal is an important part of the equation. PDE5 inhibitors like Cialis only work in the presence of nitric oxide, which is naturally released during arousal.

Other factors, including your age, diet, and overall medical history, can also affect how long it takes Cialis to kick in.

Cialis can last from 24 to 36 hours. In some cases, it can last as long as 72 hours.

This is one of the reasons Cialis has high satisfaction ratings in user surveys compared to other PDE5 inhibitors: It allows more spontaneous sexual activity.

Cialis may last longer in some people over age 65 because it takes more time for your body to process the medication. This affects how soon the drug leaves your body.

Ultimately, your experience with Cialis depends on:

  • the dose
  • the frequency of use
  • other medications you may be taking
  • other underlying health conditions
  • liver and kidney function
  • overall lifestyle
  • age

Take as directed

Take Cialis exactly as prescribed by your doctor.

For as-needed dosing, take Cialis at least 30 minutes or more before sexual activity.

If your prescription involves taking Cialis daily, take it at roughly the same time each day. This maintains steady levels of Cialis in your body.

Don’t take extra doses or change your dosing schedule without consulting your doctor.

Take as part of a healthy lifestyle

Eating a nutritious diet, being physically active, and cutting back on any substance use — including nicotine, tobacco, and alcohol — can have a positive effect on your overall health.

Taking steps to manage stress and support your intimate relationships can also improve sexual performance and well-being.

Communicate and stay relaxed

Working with a psychiatrist, therapist, or sex therapist can help you navigate strategies for the mental and emotional side of intimacy.

If you’re anxious, stressed, depressed, or nervous, Cialis may not work as well. It’s important to relax and be aroused for the medication to work best.

Alcohol

Use caution with alcohol consumption when taking Cialis. Too much alcohol can affect your ability to become aroused.

It can also cause severely low blood pressure, leading to headaches, dizziness, and fainting.

Grapefruit and grapefruit juice

Avoid grapefruit when using Cialis. It can increase the level of medication in your blood, causing severe side effects.

Heavy meals

Avoid high fat foods or heavy meals before taking Cialis and before sexual activity. Fatty or heavy foods can affect how well Cialis works, as well as how long it takes to kick in.

Nitrates and other medications

It’s important to avoid Cialis if you take certain chest pain (angina) or blood pressure medications. Nitrate medications and alpha-blockers can lower your blood pressure to dangerous levels.

Other medications may also interact with Cialis and change its effectiveness, including certain:

Be sure to talk with your doctor or pharmacist about how to take all your medications to avoid interactions. In some cases, they may recommend an alternative medication for ED.

Never discontinue a prescribed medication or start a new one without consulting a healthcare professional.

If you have a heart condition or have liver- or kidney-related problems, your doctor may need to adjust your dose of Cialis and monitor how the medication works for you.

Poor kidney function can increase Cialis levels in your body, increasing the risk of side effects. Your doctor may adjust your dose in this case.

Avoid buying Cialis without a doctor’s prescription. PDE5 medications are some of the most common counterfeit medications sold online. They can cause serious health risks.

The most common side effects of Cialis include:

  • back pain
  • diarrhea
  • headache
  • muscle aches
  • redness of the face, neck, or chest (flushing)
  • upset stomach

Serious side effects of Cialis include:

  • priapism
  • low blood pressure
  • changes in hearing and vision
When to get medical help

If you experience serious side effects, call 911 or your local emergency services.

For more information on drug interactions or side effects of Cialis, talk with your prescribing physician or pharmacist.

Remember, there are many causes for ED and many treatment options, including Cialis. Try not to be discouraged if Cialis doesn’t work the first time you use it. Your healthcare professional can help adjust the dose or recommend alternatives.

There are several PDE5 inhibitor medications available, so discuss your needs and preferences with your healthcare professional to select the medication best suited to you.