Tadalafil

What is tadalafil?

Tadalafil belongs to a class of drugs called phosphodiesterase (PDE) inhibitors. PDE inhibitors work by inhibiting certain enzymes, leading to decreased calcium levels and smooth muscle relaxation and vasodilation of the blood vessels in their targeted areas, such as the heart, genitals, and lungs. This lowers blood pressure and improves circulation in those areas.

There are four types of PDE inhibitors with different functions: PDE5, PDE4, PDE3, and nonspecific. Tadalafil is a PDE5 inhibitor and is the one most widely used. The drug is available by prescription only.

What is tadalafil used to treat?

Tadalafil is approved by the US Food and Drug Administration (FDA) for the treatment of the following conditions:

Erectile dysfunction (ED)

What You Need To Know About Erectile Dysfunction

Erectile dysfunction (ED) is the inability to achieve a firm erection or sustain it long enough for sexual intercourse. When a man is sexually stimulated, nitric oxide is released, which relaxes the smooth muscle of the corpus cavernosum and increases penile blood flow.

Tadalafil can be used to treat ED because it helps nitric oxide in its role. The drug doesn’t cause spontaneous erections, as the release of nitric oxide is triggered by sexual stimulation.¹

Benign prostatic hyperplasia (BPH)

Benign prostatic hyperplasia (BPH), also called prostate gland enlargement, causes obstruction of the urinary tract in men, leading to urination problems, such as frequency, urgency, and difficulty urinating. Tadalafil relieves some of these symptoms, delaying the need for prostate surgery to relieve the obstruction.²

Pulmonary arterial hypertension (PAH)

Pulmonary arterial hypertension (PAH) is a type of high blood pressure affecting the arteries that bring blood from the right side of the heart to the lungs. This condition is debilitating and can cause symptoms such as dizziness, shortness of breath with exertion, fainting, chest pain, and fatigue. Tadalafil relaxes the pulmonary arteries, allowing blood to flow more easily into the lungs.³

How do you take tadalafil?

Tadalafil is available in tablet form in four different dose strengths: 2.5mg, 5mg, 10mg, and 20mg. 

Three branded versions of the drug are indicated exclusively for the treatment of PAH:

• Tadliq: 20mg/5mL oral suspension

• Adcirca and ALYQ: 20mg tablet

The generic form and one branded version are indicated for the treatment of ED and BPH:

• Generic and Cialis: 2.5mg, 5mg, 10mg, 20mg tablet

Doctors prescribe the appropriate dose and form based on the condition being treated.⁴

Tadalafil is typically taken once daily to treat PAH or BPH and daily or as needed for ED.

The recommended dosing for tadalafil for its approved indications is as follows:

For the treatment of PAH (Adcirca, ALYQ, Tadliq, generic)⁵ ⁶

• 40mg once per day

For the treatment of BPH (Cialis, generic)⁷ ⁸

• 5mg daily

For the treatment of ED (Cialis, generic)⁹ ¹⁰

• As needed (before sexual activity): 5–20mg (maximum 20mg in 24 hours) OR

• Daily dosing: 2.5–5mg once daily, with a maximum daily dose of 5mg

If your doctor prescribes a daily dose of tadalafil, try to take it around the same time every day, precisely following your doctor’s instructions.

Seeing results

If you take tadalafil as needed to treat ED, it’ll start working within 15–30 minutes and remain effective for up to 36 hours. Any sexual stimulation within the period will lead to an adequate erection that is maintained during intercourse. If you take it once a day every day, the drug’s effect is continuous.

When taking tadalafil to treat BPH or PAH, results can be seen in as little as one week.¹¹

Who should not take tadalafil?

Tadalafil may not be suitable for people who:¹² ¹³

• Are allergic to it or any other medicines

• Are taking other treatments for ED

• Are taking alpha-blockers, such as doxazosin (Cardura) and prazosin (Minipress)

• Have severe heart, kidney, and liver problems

• Have had a heart attack or stroke within the past few months

• Have abnormal heart rhythms, coronary artery disease, diabetes, high cholesterol, or are at risk for bleeding

• Are being treated for hypertension or have uncontrolled high blood pressure or low blood pressure

• Are taking nitrates for chest pain or using amyl nitrate 

• Have chest pain during intercourse

• Have certain ophthalmologic conditions (hereditary retinal disease, glaucoma)

• Drink alcohol or smoke cigarettes

• Have ringing in the ears or loss of hearing

Additionally, tadalafil is not approved for people under 18 years of age.

Potential side effects of tadalafil

Like most medications, tadalafil can have mild to severe side effects.¹⁴

Although many patients taking tadalafil don't experience any side effects, the more common ones include the following:¹⁵

• Headache

• Skin flushing

• Muscle pain

• Stomach discomfort, pain, or upset

• Nausea, indigestion, belching, or heartburn

• Diarrhea

• Heartburn

• Back pain

Serious side effects from the drug include the following:¹⁶

• Fever

• Seizures

• Low blood pressure

• Swelling of the eyelids, eyes, face, or joints

• Severe peeling rash

• Reduced vision or permanent blindness

• Loss of hearing or ringing in the ears

• Prolonged or painful erections

• Stroke

• Chest pain or heart attack

• Difficulty breathing

The side effects people experience tend to increase with the dosage. This list is not comprehensive. If you notice other effects that aren't listed above but think they are connected to your taking tadalafil, contact your doctor for an evaluation of your condition.

Overdose

It is possible to overdose on tadalafil and experience toxic side effects. Symptoms may include any of the above adverse effects or:

• Collapsing or fainting

• Trouble breathing

• Seizure

• Severely low blood pressure

• Painful or prolonged erection

If you or someone else exhibits severe symptoms after taking tadalafil, call for emergency assistance at 911. For more information, you can also call the National Poison Control helpline at 1-800-222-1222.

Allergy information

Tadalafil can trigger an allergic reaction in some people, resulting in symptoms ranging from mild to severe. Symptoms of a drug allergy may include any of the following:

• Rash

• Hives

• Swelling of the lips, tongue, or throat

• Difficulty swallowing

• Difficulty breathing

• Flushing

• Vomiting

• Loss of consciousness

If you notice any mild signs of an allergic reaction, seek medical help from your doctor. They may recommend ways to ease the allergic reaction. However, if you experience severe symptoms that could lead to a medical emergency, call 911 immediately.

Long-term use of tadalafil

Evidence suggests that tadalafil remains safe and effective when taken as needed for up to two years. More research is needed on the effects of long-term daily use. If taken as prescribed, most people do not experience serious adverse effects.¹⁷

Tadalafil and pregnancy

Tadalafil used to treat PAH has been designated a pregnancy category B drug by the US FDA. Tadalafil used to treat ED and BPH has not been assigned a category.

There are no adequate and well-controlled human studies on the effects of taking tadalafil during pregnancy, but animal studies have shown no negative outcomes. Nonetheless, some authorities say it should be avoided during pregnancy and breastfeeding unless the benefits outweigh the risks. Untreated PAH during pregnancy can lead to serious conditions, including stroke or heart failure.¹⁸

Missed doses

If you take tadalafil daily to treat ED or BPH and miss a dose, take it as soon as you remember, then continue as usual. But if it’s nearly time for your next dose, skip the missed dose, as taking too much could lead to toxicity.

Drug interactions

Several drugs interact with tadalafil, changing how it works or causing side effects. These drugs include the following:¹⁹ ²⁰

• Riociguat (Adempas)

• Drugs for the treatment of hepatitis C, such as boceprevir (Victrelis) and telaprevir (Incivek)

• Drugs for heart failure, such as vericiguat (Verquvo)

• Nitrates for chest pain, such as nitroglycerin (Nitrostat) and isosorbide dinitrate (Isordil), because they can cause very low blood pressure

• Drugs for hypertension or prostate disease known as alpha-adrenergic blockers, such as doxazosin (Cardura) and terazosin (Hytrin)

• Drugs for HIV, such as ritonavir (Norvir, Kaletra)

• Antifungal medications, such as ketoconazole (Nizoral) and itraconazole (Sporanox)

• Antibiotics, such as clarithromycin (Biaxin), rifampin, and erythromycin

• Anti-seizure medications like carbamazepine (Tegretol), phenobarbital, and phenytoin (Dilantin)

This list is not comprehensive. Take note of all drugs you use regularly and occasionally to share with your pharmacist or doctor. Don't start, change, or stop medicines without consulting your doctor.

Can I drink alcohol while taking tadalafil?

When taking tadalafil, alcohol consumption can lead to harmful effects. You may experience lightheadedness, headache, nausea, low blood pressure, heart palpitations, dizziness, fainting, and flushing. You should limit or avoid drinking alcohol when taking tadalafil. Make sure to discuss your alcohol use with your physician before taking the drug.²¹

What to discuss with your doctor before starting tadalafil

Tadalafil is available by prescription only, so you’ll need to meet with your doctor before you start taking it. At your appointment, you should discuss the following topics:²²

• Medication or ingredient allergies

• Prescription and nonprescription medications you currently take, including supplements, herbs, and vitamins

• Existing and past medical conditions, such as heart disease, heart rhythm disturbance, stroke, stomach ulcer, high blood pressure, bleeding disorder or blood disease, liver or kidney disease

• If you have had chest pain during intercourse or were told not to have intercourse due to your health problems

• If you’ve ever had eye disease or severe vision loss

• If you're pregnant, breastfeeding, or trying to conceive

• If you drink alcohol or use recreational drugs, such as marijuana, and the frequency

• If you're planning to have surgery or any medical procedures, including dental

If you see another doctor for any reason, tell them you are taking tadalafil.

Stopping tadalafil

You should not stop taking tadalafil without consulting your doctor, even if you feel well. If you have a reason to stop, tell your doctor about your concerns. They may suggest an alternative drug, slowly wean the dose, or monitor you closely after stopping.

Drug approval history

2003: The US FDA approves tadalafil for medical use²³

Tips for taking tadalafil

These tips can help you take tadalafil effectively and safely:

• Always follow your doctor's prescription.

• Take tadalafil at around the same time every day.

• You can take tadalafil with or without food.

• Avoid drinking alcohol, or limit your intake while being treated with tadalafil.

• Do not take nitrates within 48 hours of the last dose of tadalafil.²⁴

• Inform your doctor about your medical history and every medication you are taking or if you start a new medicine. This will help to limit drug interactions, which can cause adverse effects or lower the medication’s effectiveness.

• Store your medicine between 59° and 86°F (15° and 30°C).

• Avoid taking tadalafil while pregnant or breastfeeding unless your doctor recommends it.

Frequently asked questions

Should I avoid certain foods while taking tadalafil?

Avoid grapefruit juice or grapefruit-containing foods as they may increase the side effects of tadalafil.²⁵

What happens if you take tadalafil and you don't need it?

If you take tadalafil when you don’t need it, you may develop tolerance to the medication, so when you need it, it may not work.

Does caffeine affect tadalafil?

No, there are no known interactions between caffeine and tadalafil.

How does tadalafil affect the brain?

Research indicates tadalafil may improve brain function in patients taking it for BPH and ED.²⁶