Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor a class of medicines that relax and widen blood vessels in specific tissues. Originally developed and approved for erectile dysfunction (ED) in 2003, it was subsequently approved for two additional conditions: benign prostatic hyperplasia (BPH) and pulmonary arterial hypertension (PAH ).  Tadalafil is notable for its exceptionally long duration of action up to 36 hours which distinguishes it from other PDE5 inhibitors and has led to its nickname "the weekend pill." It is available as 2.5 mg, 5 mg, 10 mg and 20 mg tablets.

How Does Tadalafil Work?

Sexual stimulation releases nitric oxide, triggering cGMP (cyclic guanosine monophosphate) - a messenger that relaxes smooth muscle in blood vessels. PDE5 normally breaks cGMP down ending the erection. Tadalafil inhibits PDE5, sustaining the relaxation. Stimulation is still required. The same mechanism relaxes lung blood vessels (reducing PAH pressure) and prostate smooth muscle (easing BPH symptoms).

Uses of Tadalafil

Doctors use tadalafil for the following conditions:

• ED (erectile dysfunction): Inability to achieve or maintain an erection sufficient for sexual activity.

• BPH (benign prostatic hyperplasia): Enlarged prostate causing urinary symptoms like frequent urination, weak stream, incomplete emptying and urgency.

• Combined ED and BPH: Treats both conditions simultaneously.

• Pulmonary arterial hypertension (PAH): Reduces pulmonary vascular resistance (the pressure the right heart must overcome) improving exercise capacity.

How and When to Take Tadalafil

You can take tadalafil with or without food. The medication should not be taken more frequently than recommended. Avoid grapefruit juice within 24 hours as it inhibits CYP3A4 (the metabolising enzyme) and raises blood levels unpredictably.

Side Effects of Tadalafil

Common effects:

• Headache 

• Back pain and myalgia (muscle aches) 

• Facial flushing

• Indigestion

• Nasal congestion

• Mild dizziness.

Serious but rare:

• Sudden vision loss - a rare condition called NAION (non-arteritic anterior ischaemic optic neuropathy) is associated with PDE5 inhibitors

• Sudden hearing loss, sometimes with tinnitus (ringing in the ears)

• Priapism - a painful erection lasting over 4 hours

• Severe blood pressure drop.

Can Tadalafil Be Taken Daily?

Yes 2.5 mg and 5 mg are approved for daily use, suited to men with frequent sexual activity, those who prefer spontaneity and those treating BPH. For PAH, 40 mg daily is the recommended regimen.

Precautions While Using Tadalafil

Tell your doctor before taking tadalafil about:

• Nitrates is absolute contraindication

• Recent cardiovascular events like a heart attack within 90 days, a stroke within 6 months, unstable angina, severe heart failure, or dangerous arrhythmias

• Taking alpha-blockers like tamsulosin, prazosin, and doxazosin

• Severe liver or kidney impairment 

• Retinitis pigmentosa 

• Blood cell disorders like sickle cell anaemia, multiple myeloma, and leukaemia 

Not for use in women or children.

What If You Miss a Dose?

• On-demand: Take when needed, no more than once in 24 hours. 

• Daily use: Take the missed dose the same day; if not until the next day, skip it. Do not double up.

What If You Overdose?

Overdose raises the risk of marked blood pressure drop, severe headache, priapism, and visual disturbance. Go to the nearest emergency hospital immediately.

Caution With Other Drugs: Interactions

Key interactions are:

• Nitrates like GTN spray, isosorbide, and amyl nitrite

• Alpha-blockers 

• Antihypertensives 

• Strong CYP3A4 inhibitors like ketoconazole, ritonavir, and clarithromycin

• Strong CYP3A4 inducers like rifampicin, carbamazepine, and phenytoin

• Other PDE5 inhibitors like sildenafil, vardenafil

• Alcohol as increases dizziness; heavy drinking worsens erectile function.

Dosage for Tadalafil

• ED (on-demand): 10 mg (or 20 mg if needed) 30-60 minutes before activity; one dose per 24 hours

• ED (daily): 2.5 mg once daily; increase to 5 mg if needed

• BPH or combined ED/BPH: 5 mg once daily

• PAH: 40 mg once daily (two 20 mg tablets).

Tadalafil vs Sildenafil

Both are PDE5 inhibitors for ED. Key differences:

• Duration: Tadalafil up to 36 hours; sildenafil 4–6 hours. Therefore tadalafil is more flexible for timing

• Food: High-fat meals significantly reduce sildenafil absorption

• Daily dosing: Tadalafil approved at 2.5–5 mg daily for ED; sildenafil is not approved for daily ED dosing

• Additional indications: Tadalafil covers BPH and PAH; sildenafil covers PAH (as Revatio) but not BPH

• Back pain and myalgia: More commonly reported with tadalafil

• Visual side effects: Blue-tinted vision (cyanopsia) is more common with sildenafil, which inhibits retinal PDE6 more than tadalafil.

FAQs 

1. What is tadalafil used for?

Tadalafil treats erectile dysfunction (ED), benign prostatic hyperplasia and pulmonary arterial hypertension - all by relaxing smooth muscle in blood vessels.

2. How long does tadalafil last in the body?

Tadalafil has a half-life (the time taken for blood levels to halve) of approximately 17.5 hours that is the longest of any PDE5 inhibitor. Its clinical effects (the window during which an erection in response to sexual stimulation is supported) can last up to 36 hours after a 10 mg or 20 mg dose. This is why it is sometimes called "the weekend pill."

3. What are the side effects of tadalafil tablets?

Common effects: headache, back pain, flushing, nasal congestion, and indigestion. 

Serious but rare: sudden vision or hearing loss, priapism and severe blood pressure drop with nitrates or alpha-blockers.

4. How should tadalafil be taken for erectile dysfunction?

On-demand: 10 mg (or 20 mg if needed) 30–60 minutes before activity; no more than one dose per 24 hours. 

Daily: 2.5–5 mg at the same time each day, removing the need to plan a dose.

5. Can tadalafil be taken daily?

Yes 2.5 mg and 5 mg are approved for daily use in ED and BPH. Steady blood levels make the timing of sexual activity irrelevant; well tolerated long-term. The 10 mg and 20 mg doses are for on-demand use only.

6. Is tadalafil the same as Cialis?

Tadalafil is the active ingredient; Cialis is the original brand name by Eli Lilly. Generic tadalafil widely available in India contains the same molecule at the same dose with identical effect and duration.

7. Can tadalafil improve sexual performance?

Tadalafil improves the ability to achieve and maintain an erection in response to stimulation but does not increase libido or stamina. It requires stimulation to work and does not cause erections independently. Men without erectile dysfunction do not benefit from it.

8. Is tadalafil safe for heart patients?

Not for all heart patients. Men with stable coronary artery disease tolerating moderate physical activity generally use it safely. Absolute contraindication with nitrates as combining causes a potentially fatal blood pressure drop. Men with a recent heart attack, stroke, uncontrolled heart failure, or dangerous arrhythmias need specialist assessment.

9. Can tadalafil cause headache or back pain?

Yes headache is the most common side effect, caused by blood vessel widening. Back pain and myalgia (more frequent with tadalafil than other PDE5 inhibitors) typically appear 12–24 hours after the dose and resolve within 24–48 hours. Persistent or severe back pain needs medical review.

10. How long before sex should tadalafil be taken?

Take the 10 mg or 20 mg dose at least 30 minutes before activity; peak effect is at 1–2 hours. Because the effect lasts 36 hours, timing is flexible within that window. For daily dosing (2.5 mg or 5 mg), timing relative to sex is irrelevant.