# Tadalafil: what it is, what it is approved for and how it works > Tadalafil is a prescription PDE5 inhibitor, sold by Eli Lilly as Cialis and as FDA-approved generics. The FDA approved it for erectile dysfunction, for the urinary symptoms of an enlarged prostate (BPH), and for both together. It supports the body's own arousal signal, so it works only with sexual stimulation, and it must never be combined with nitrates. _Last updated: 2026-10-18_ --- Status: FDA-approved prescription medicine for ED. Source: Cialis prescribing information (Eli Lilly), DailyMed, checked 2026-10-17. **In short:** tadalafil is a prescription medicine that blocks an enzyme called PDE5. Eli Lilly sells it as Cialis, with an initial US approval in 2003, and the label lists three approved uses: erectile dysfunction, the signs and symptoms of benign prostatic hyperplasia (BPH, an enlarged prostate), and both conditions together ([Cialis label, DailyMed](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). It does not cause an erection by itself, it does not raise desire, and it is not safe for everyone. This page is the starting point for everything The ED Report covers about tadalafil, with each answer taken from the label or another primary source. | Question | Short answer | Where it comes from | | ----------------------------- | ------------------------------------------------------------------------------ | ------------------------------------ | | What kind of drug is it? | A phosphodiesterase type 5 (PDE5) inhibitor taken by mouth as a tablet | Cialis label, sections 1 and 11 | | What is it approved for? | ED, the urinary symptoms of BPH, and ED with BPH; as Adcirca, a lung condition | Cialis and Adcirca labels, section 1 | | Does it work without arousal? | No; the label says it has no effect without sexual stimulation | Cialis label, section 12.1 | | Is it a prescription drug? | Yes, in the US, and only for men over 18 | Cialis patient information | | Who must never take it? | Men using nitrates or "poppers", or the lung drug riociguat | Cialis label, section 4 | | First US approval | 2003 | Cialis label, highlights | ## What is tadalafil? Tadalafil is a prescription medicine in the phosphodiesterase type 5 (PDE5) inhibitor class, and Cialis is Eli Lilly's brand name for it. The label describes it as "a selective inhibitor" of PDE5, supplied as almond-shaped yellow tablets for oral use ([Cialis label, sections 3 and 11](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). MedlinePlus, the National Library of Medicine's drug guide, lists three US brand names that contain it: Cialis, Adcirca, and Entadfi, a combination product that also contains finasteride ([MedlinePlus, Tadalafil](https://medlineplus.gov/druginfo/meds/a604008.html)). Tadalafil is the ingredient; the brand tells you which condition the product was approved for. ## What is Cialis? Cialis is Eli Lilly's brand of tadalafil for erectile dysfunction and enlarged-prostate symptoms. The patient information calls it "a prescription medicine taken by mouth" for men with ED, men with symptoms of BPH, and men with both, and says it is only for men over the age of 18 and is not for women or children ([Cialis label, Patient Information](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). FDA-approved generic tadalafil carries the same ingredient, and our page on [generic Cialis](/generic-cialis/) explains what a generic has to prove and why a compounded version is a different thing. The FDA states plainly that "compounded drugs are not FDA-approved" ([FDA, Compounding and the FDA](https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers)). ## What is tadalafil used for: ED, BPH or both? Tadalafil is approved for all three: ED alone, BPH symptoms alone, and ED with BPH symptoms in the same man. The Cialis label's indications read "the treatment of erectile dysfunction (ED)", "the signs and symptoms of benign prostatic hyperplasia (BPH)", and ED together with BPH symptoms ([Cialis label, sections 1.1 to 1.3](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). MedlinePlus describes the BPH symptoms in plain terms: difficulty urinating (hesitation, dribbling, a weak stream, incomplete emptying), painful urination, and urinary frequency and urgency ([MedlinePlus, Tadalafil](https://medlineplus.gov/druginfo/meds/a604008.html)). The label adds one limit. When tadalafil is started together with finasteride for BPH, it recommends the pairing for up to 26 weeks only, because the extra benefit from tadalafil shrank between week 4 and week 26 of the study and "the incremental benefit of CIALIS beyond 26 weeks is unknown" ([Cialis label, sections 1.4 and 14](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). The same ingredient also has a separate approval under another brand, as shown below. | Brand or product | Approved for | Source | | ------------------ | ------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------- | | Cialis (Eli Lilly) | ED; BPH symptoms; ED with BPH symptoms | [Cialis label](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895) | | Adcirca | Pulmonary arterial hypertension, to improve exercise ability | [Adcirca label](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ff61b237-be8e-461b-8114-78c52a8ad0ae) | | Entadfi | A combination of finasteride and tadalafil | [MedlinePlus](https://medlineplus.gov/druginfo/meds/a604008.html) | The patient information is clear that a man should not take Cialis and Adcirca at the same time ([Cialis label, Patient Information](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). ## How does tadalafil work? Tadalafil works by protecting a chemical messenger the body already makes during arousal. The label sets out the chain: sexual stimulation releases nitric oxide from nerve endings and the lining of blood vessels, nitric oxide raises a messenger called cGMP, and cGMP relaxes the smooth muscle so more blood flows into the erectile tissue; PDE5 breaks cGMP down, and tadalafil blocks PDE5 ([Cialis label, section 12.1](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). Because the first step needs arousal, the label says tadalafil "has no effect in the absence of sexual stimulation." For BPH, the same enzyme block reaches the smooth muscle of the prostate, the bladder and their blood supply, but the label is candid that "the mechanism for reducing BPH symptoms has not been established." PDE5 is also found in blood vessels, the lungs, platelets and other tissues ([Cialis label, section 12.1](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). The Adcirca label adds that PDE5 is the main enzyme of its kind in the blood vessels of the lungs, which is how the same drug, as Adcirca, treats pulmonary arterial hypertension ([Adcirca label, section 12.1](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ff61b237-be8e-461b-8114-78c52a8ad0ae)). ## How does Cialis work differently from other ED pills? What stands out on the Cialis label is how slowly the body clears tadalafil. The label gives a mean terminal half-life of 17.5 hours in healthy men, and the patient information notes that after a single tablet "some of the active ingredient of CIALIS remains in your body for more than 2 days" ([Cialis label, section 12.3 and Patient Information](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). The label also says food does not change how it is absorbed, so it can be taken with or without meals. The label describes two ways to use it for ED, as needed or once daily, and the choice and the amount are set by the prescriber, not by a website. Our pages on [how long tadalafil lasts](/how-long-does-tadalafil-last/) and [daily versus on-demand tadalafil](/daily-vs-on-demand-tadalafil/) go into each, and [tadalafil vs sildenafil](/tadalafil-vs-sildenafil/) compares the two side by side. ## How well does tadalafil work? In the trials behind its approval, tadalafil improved erections more than placebo across many groups of men. The label summarizes 22 clinical trials of up to 24 weeks involving more than 4,000 men with ED. In its 7 main 12-week studies, which included men with ED of different severities and causes, tadalafil showed statistically significant improvement over placebo in the ability to get and keep an erection; the label adds that "the treatment effect of CIALIS did not diminish over time" ([Cialis label, section 14.1](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). Separate trials found significant improvement in men with ED who also had diabetes and in men with ED after nerve-sparing prostate surgery. For BPH, two 12-week trials in men with BPH found that tadalafil improved the International Prostate Symptom Score significantly more than placebo ([Cialis label, section 14.3](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). These are average results from groups in trials, not a prediction for any one man. The AUA guideline also notes that PDE5 inhibitors "only mitigate symptoms rather than curing the underlying condition" ([AUA Erectile Dysfunction guideline](https://www.auanet.org/guidelines-and-quality/guidelines/erectile-dysfunction-%28ed%29-guideline)). ## What is the downside of tadalafil? The main downsides are side effects for some men, a hard rule against nitrates, and the fact that it treats the symptom rather than the cause. The patient information lists the most common side effects as "headache, indigestion, back pain, muscle aches, flushing, and stuffy or runny nose," and says back pain and muscle aches usually start 12 to 24 hours after a dose and go away within 2 days ([Cialis label, Patient Information](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). In the eight main 12-week as-needed trials, 3.1% of men on the two higher strengths tested stopped because of side effects, compared with 1.4% on placebo ([Cialis label, section 6.1](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). | Side effect (as-needed ED trials) | Tadalafil, across the strengths studied | Placebo | | --------------------------------- | --------------------------------------- | ------- | | Headache | 11% to 15% | 5% | | Indigestion | 4% to 10% | 1% | | Back pain | 3% to 6% | 3% | | Muscle aches | 1% to 4% | 1% | | Stuffy nose | 2% to 3% | 1% | | Flushing | 2% to 3% | 1% | Source: [Cialis label, Table 1](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895). The full list, the rarer events and the daily-use figures are on our [tadalafil side effects](/tadalafil-side-effects/) page. The long half-life is a downside too. Because tadalafil stays in the body for days, the label warns that if a man who has taken it develops chest pain that might need nitroglycerin, he should get emergency care rather than reach for a nitrate himself ([Cialis label, sections 4.1 and 5.1](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). The label also cautions that substantial alcohol, alpha-blockers and other blood pressure medicines can add to its blood-pressure-lowering effect. Our [tadalafil drug interactions](/tadalafil-drug-interactions/) page covers each one. ## Who should not take tadalafil? Men who use any nitrate medicine, "poppers", or the lung drug riociguat must not take tadalafil, and neither should anyone with a known serious allergy to it. The label explains that tadalafil can make nitrates drop blood pressure to an unsafe level, which the patient information says could cause dizziness, fainting, a heart attack or a stroke ([Cialis label, section 4 and Patient Information](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). The label also says it should not be used by men for whom sexual activity is inadvisable because of their heart health, and it is not recommended for certain groups left out of the trials, such as men who had a heart attack within the last 90 days. The patient information asks every man to tell his provider about heart problems, a past stroke, low or uncontrolled high blood pressure, liver or kidney problems, past severe vision loss, stomach ulcers, a bleeding problem, Peyronie's disease, or blood cell problems such as sickle cell anemia. MedlinePlus adds that tadalafil does not cure ED, does not increase desire, and does not protect against sexually transmitted infections ([MedlinePlus, Tadalafil](https://medlineplus.gov/druginfo/meds/a604008.html)). ## Does tadalafil expire? Yes. Tadalafil tablets carry an expiration date, and the FDA's advice is direct: "If your medicine has expired, do not use it" ([FDA, Don't Be Tempted to Use Expired Medicines](https://www.fda.gov/drugs/safe-disposal-medicines/dont-be-tempted-use-expired-medicines)). The FDA explains that expired medicines can be less effective or risky "due to a change in chemical composition or a decrease in strength," and that once the date has passed "there is no guarantee that the medicine will be safe and effective." Storage matters too. The Cialis label says to store the tablets at room temperature, between 59 and 86°F (15 and 30°C), out of the reach of children ([Cialis label, section 16.2 and Patient Information](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)), and MedlinePlus adds to keep them in the original container, tightly closed and away from heat and moisture, "not in the bathroom" ([MedlinePlus, Tadalafil](https://medlineplus.gov/druginfo/meds/a604008.html)). For disposal, the FDA prefers a drug take-back location or a mail-back envelope. The same rules apply to the other ED pills; our page on [how sildenafil (Viagra) expiry works](/does-sildenafil-expire) covers what is known about using tablets past the date. ## Is tadalafil sold without a prescription? No. In the US tadalafil for ED is a prescription medicine, and the patient information says it "must be used only under a healthcare provider's care" ([Cialis label, Patient Information](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). The FDA warns that many products that claim to treat ED or enhance sexual performance, sometimes advertised as supplements or "all-natural" treatments, are likely to be contaminated with dangerous hidden ingredients, and that its list covers "only a small fraction" of them ([FDA, Tainted Sexual Enhancement Products](https://www.fda.gov/drugs/medication-health-fraud/tainted-sexual-enhancement-products)). A pill from an unknown seller is not a reliable way to get tadalafil. An FDA-approved generic from a licensed pharmacy is a different matter, which our guide on [is generic Cialis safe](/are-generic-ed-medications-safe) explains, and our guide to [is it safe to buy Cialis online](/getting-ed-treatment-online-safely) covers how to check a seller. Get emergency help for an erection lasting more than 4 hours, painful or not. Stop tadalafil and get prompt medical attention for sudden loss of vision in one or both eyes, or a sudden drop or loss of hearing. If chest pain, dizziness or nausea starts during sex, stop and get medical help, and tell the treating team when you last took tadalafil, because it stays in the body for days and matters for emergency heart care. ## When should you talk to a clinician about tadalafil? Before starting it, and whenever your health or your other medicines change. The label asks prescribers to look for the underlying cause first: "Evaluation of erectile dysfunction and BPH should include an appropriate medical assessment to identify potential underlying causes" ([Cialis label, section 5](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895)). NIDDK makes the same point from the other side: health care professionals treat the underlying cause of ED when possible, and you should not stop any prescribed medicine on your own ([NIDDK, Treatment for Erectile Dysfunction](https://www.niddk.nih.gov/health-information/urologic-diseases/erectile-dysfunction/treatment)). The AUA guideline recommends that men with ED be told about FDA-approved oral PDE5 inhibitors, "including discussion of benefits and risks/burdens, unless contraindicated" ([AUA Erectile Dysfunction guideline](https://www.auanet.org/guidelines-and-quality/guidelines/erectile-dysfunction-%28ed%29-guideline)). That conversation can happen in person or through a licensed telehealth service. Whether tadalafil fits you, and how to take it, is a decision for you and the prescriber, made with your full medical history in view. ## Sources 1. [Cialis (tadalafil) tablets, prescribing information and patient information, Eli Lilly, DailyMed](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bcd8f8ab-81a2-4891-83db-24a0b0e25895): indications (1.1 to 1.4), contraindications, warnings, side effects, mechanism (12.1), pharmacokinetics (12.3), clinical studies (14), storage (16.2). 2. [Adcirca (tadalafil) tablets, prescribing information, DailyMed](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ff61b237-be8e-461b-8114-78c52a8ad0ae): the pulmonary arterial hypertension indication. 3. [Tadalafil, MedlinePlus Drug Information, US National Library of Medicine](https://medlineplus.gov/druginfo/meds/a604008.html): brand names, plain-language uses, precautions and storage. 4. [Treatment for Erectile Dysfunction, National Institute of Diabetes and Digestive and Kidney Diseases](https://www.niddk.nih.gov/health-information/urologic-diseases/erectile-dysfunction/treatment): treating the underlying cause, not stopping medicines on your own. 5. [Erectile Dysfunction: AUA Guideline, American Urological Association](https://www.auanet.org/guidelines-and-quality/guidelines/erectile-dysfunction-%28ed%29-guideline): PDE5 inhibitors as an option to discuss, and their limits. 6. [Don't Be Tempted to Use Expired Medicines, US Food and Drug Administration](https://www.fda.gov/drugs/safe-disposal-medicines/dont-be-tempted-use-expired-medicines): expiration dates, storage and disposal. 7. [Compounding and the FDA: Questions and Answers, US Food and Drug Administration](https://www.fda.gov/drugs/human-drug-compounding/compounding-and-fda-questions-and-answers): compounded drugs are not FDA-approved. 8. [Tainted Sexual Enhancement Products, US Food and Drug Administration](https://www.fda.gov/drugs/medication-health-fraud/tainted-sexual-enhancement-products): hidden drug ingredients in sexual enhancement products. --- _Affiliate disclosure: some links on the web version of this site go to Bodybuilding Peptides (trybbpeptides.com), an affiliate destination, and we may earn a commission if you buy there. Our coverage is independent of that relationship. Details: https://theedreport.com/affiliate-disclosure/_