People looking for information on erectile dysfunction medication often come across the name Tadalafil, yet many are unsure how it works, whether it is safe, and how it differs from other drugs. This article gathers the key information in an easy-to-understand form — from how it works, dosage, and side effects to precautions — so you can consult a doctor with confidence.
Sexual performance is a health topic that can be discussed normally; it is nothing to be ashamed of. Quite a few men face this problem at some point in life, and having accurate knowledge is a good starting point for taking care of yourself.
What is Tadalafil and What Does It Treat?
Tadalafil is a medication in the phosphodiesterase type 5 inhibitor (PDE 5 inhibitor) class. It is used mainly to treat erectile dysfunction (ED), and it is also used to treat benign prostatic hyperplasia (BPH) and pulmonary arterial hypertension.
This medication is known under the brand name Cialis for the ED and enlarged-prostate indications, while for pulmonary arterial hypertension it is sold under the brand name Adcirca. Tadalafil was developed by Eli Lilly.
Tadalafil has three main approved indications: treating erectile dysfunction in men, relieving the symptoms of an enlarged prostate such as difficulty urinating or frequent urination, and treating pulmonary arterial hypertension that causes easy fatigue. The doctor will choose the indication and dose that suit each individual’s symptoms.
The U.S. Food and Drug Administration (FDA) has approved Tadalafil for treating ED since 2003. In Thailand, the medication is registered with the Food and Drug Administration (Thai FDA) for example, Cialis film-coated tablets at 5 mg, registration number 1C 28/63(N).
Tadalafil is a classified as a “specially controlled medication” under the announcements of the Thai FDA. It must be prescribed by a doctor and its sales are reported to the FDA, so it cannot be bought over the counter at a general pharmacy. It should note be purchased from unlicensed online sources, because of the risk of counterfeit or substandard medication.
What Is Erectile Dysfunction (ED) and What Causes It?
Erectile dysfunction (ED) is a condition in which the penis does not become firm enough, or does not stay firm long enough, for sexual intercourse on a consistent basis. This condition is common and is often linked to overall vascular health, so it is not merely a sexual problem.
The Massachusetts Male Aging Study found that about 52% of men aged 40–70 had some degree of ED, with the risk rising with age. This figure reflects that ED is a normal, treatable condition — not something you have to keep to yourself.
The causes of ED fall into two main groups. The first is physical causes, such as diabetes, high blood pressure, high blood lipids, cardiovascular disease, low male hormone levels, and the effects of smoking. The second is psychological causes, such as stress, anxiety, depression, and relationship problems.
Common risk factors include increasing age, smoking, excessive alcohol consumption, being overweight, and a lack of exercise. People with diabetes have about four times the risk of developing ED compared with the general population, and often have more severe symptoms. Understanding the cause helps the doctor plan treatment precisely, rather than simply prescribing medication
How Does Tadalafil Work?
Tadalafil works by inhibiting the PDE5 enzyme, allowing the blood vessels around the penis to dilate better and for longer, so blood flows in sufficiently for an erection. However, the medication only takes effect when there is also sexual stimulation.
When sexual stimulation occurs, the body releases nitric oxide, which relaxes the blood vessels. This substance triggers the production of cGMP, which dilates the blood vessels, The PDE5 enzyme is responsible for breaking down cGMP; when the medication inhibits this enzyme, cGMP last longer, so the blood vessels stay dilated long enough for and erection.
A common misconception is that this medication creates sexual arousal on its own, but in reality it does not. If the user has no sexual stimulation, the medication will not produce an erection. The drug is therefore an aid that supports the body’s own function, not a creator of arousal.
Tadalafil is metabolized in the liver mainly through the CYP3A4 enzyme. This point is important because certain drugs or foods that interfere with this enzyme can change the drug’s level in the blood as explained in the section on drugs that must not be together.
How Is Tadalafil Different for Sildenafil (Viagra)?
The main difference is the duration of action: Tadalafil stays active in the body for up to 36 hours, while Sildenafil lasts about 6–8 hours. In addition, food does not affect the absorption of Tadalafil, so Tadalafil can be taken with meals — unlike Sildenafil, which should be taken on an empty stomach because taking Sildenafil with food reduces its absorption.
Tadalafil has a half-life of about 17.5 hours, much longer than other drugs in the same class, which is why it has the nickname “the weekend pill” — a single dose covers a long window, helping couples avoid worrying about timing and making their time together feel more natural.
| Item | Tadalafil | Sildenafil |
|---|---|---|
| Brand name | Cialis | Viagra |
| Duration of action | Up to 36 hours | 6-8 hours |
| Onset of action | ~30-45 minutes | ~30-60 minutes |
| effect of food on absorption | Food has no effect on absorption | Food reduces absporption |
| Daily use | Starts at 2.5-5 mg/day | Not common |
| On-demand use | Starts at 10 mg | Starts at 25 mg |
| Maximum does within 24 hrs | No more that 20 mg | No more that 100 mg |
Choosing a medication is not about which one is “better” but about each person’s lifestyle and health. Those who want flexibility with timing may suit Tadalafil, while those who use it occationally and for whom a shorter duration is enough may suit Sildenafil, A doctor will help assess and choose what fits you.
Tadalafil Dosage and Correct Use
The on-demand Tadalafil dose starts at 10 mg, taken at least 30 minutes before sexual activity, while the daily dose is 2.5–5 mg taken once a day at the same time. In all cases it must not be taken more than once a day.
The doctor will choose the dose and form that suit each individual. In general there are two approaches.
On-demand
The starting dose is 10 mg, taken at least 30 minutes before sexual activity. The doctor may increase it to 20 mg or reduce it to 5 mg depending on the response and side effects. The maximum dose approved by the FDA for this approach is 20 mg, and it should not be taken more often than once a day. This approach suits those who have sex less frequently.
Daily Use
A dose of 2.5-5 mg is taken once a day at the same time every day, independent of the timing of sexual activity. This approach suits those who have frequent sexual activity, or those who also want to treat and enlarged prostate. The advantage is that the drug level in the body stays steady, keeping you ready for sexual activity at any time without planning ahead.
Tadalafil can be taken before or after meals, because eating does not interfere with the drug’s absorption — unlike Sildenafil, where eating interferes with absorption and reduces the amount of drug absorbed into the body. In addition, Tadalafil should be swallowed whole with plain water; do not crush or split the tablet unless instructed by a doctor.
What to Do If You Miss a Dose or Take Too Much
For the daily approach, if you miss a dose, take it as soon as you remember. But if it is almost time for the next dose, skip the missed dose entirely. Do not take two tablets to make up for it, as this increases the risk of side effects. The on-demand approach has no issue with missed doses, since it is taken only when needed.
If you take too much and have abnormal symptoms such as severe dizziness, fainting, chest pain, or an abnormally prolonged erection, go to the hospital immediately. Taking more than the recommended dose does not improve results — it only increases the risk.
How Does Tadalafil Treat an Enlarged Prostate (BPH)?
Tadalafil at 5 mg taken daily helps relieve the symptoms of benign prostatic hyperplasia (BPH), such as difficulty urinating, frequent urination, incomplete urination, or having to wake up to urinate at night, by relaxing the muscles around the prostate and bladder.
An enlarged prostate is common in middle-aged and older men, and often occurs together with ED. A key advantage of Tadalafil is that it can treat both conditions at once with a single medication, making it a convenient option for those who have both symptoms.
Using Tadalafil for BPH must be under a doctor’s supervision, because abnormal urinary symptoms may come from other causes that require further examination. The doctor will first assess whether the symptoms genuinely come from an enlarged prostate, rather than another condition that needs different treatment.
How Effective Is Tadalafil?
Tadalafil is a medication backed by a large body of study data. PDE5 inhibitors help about 60-70% of men without diabetes achieve improved erections sufficient for intercourse. This figure is considered satisfactory for an ED medication.
The drug’s effectiveness depends on many factors, such as the cause of ED, the severity of symptoms, and underlying conditions. People with diabetes may respond slightly less, because ED in this group is often more severe but studies have found that Tadalafil remains effective and safe in diabetic patients as well.
If the medication does not work the first time, it does not necessarily mean the drug will not work at all. Sometimes it takes several attempts or a dose adjustment. Consulting a doctor to review how it is used and to find the true cause is more important than increasing the dose yourself.
What Are the Side Effects of Tadalafil?
Common side effects of Tadalafil include headache, indigestion, back pain, muscle pain, nasal congestion, flushing, and dizziness. These symptoms are usually mild and gradually improve on their own. Serious side effects are rare but require seeing a doctor immediately.
Back pain and muscle pain are side effects found more with Tadalafil than with other drugs in the same class. They usually occur within 12–24 hours after taking the medication and resolve on their own within 48 hours. This symptom is believed to be related to the drug slightly inhibiting another enzyme, but overall it is not considered dangerous.
Signs that you should stop the medication and see a doctor immediately include an erection lasting more than 4 hours (priapism), sudden changes in vision or hearing, chest pain, or difficulty breathing. If you have an allergic reaction such as a rash, facial swelling, or swollen lips, go to the hospital immediately.
An erection lasting more than 4 hours is an emergency that must be treated quickly, because if left untreated it can cause permanent tissue damage. Although very rare, users should be aware of this sign.
Drugs and Foods That Must Not Be Used with Tadalafil
The drugs that absolutely must not be used with Tadalafil are nitrates (used for heart disease) and Riociguat (used to treat pulmonary hypertension), because they cause a severe, life-threatening drop in blood pressure. It also must not be used together with other ED drugs in the same class.
Drugs and substances to be careful with when used with Tadalafil are as follows:
- Nitrates: Absolutely must not be combined — risk of a severe drop in blood pressure.
- Riociguat (Adempas): Must not be combined — risk of a drop in blood pressure.
- Other ED drugs such as Sildenafil, Vardenafil, Avanafil: Must not be used together, because of overlapping action.
- Alpha-blocker blood-pressure drugs: Must start at a low dose and keep blood pressure stable first.
- Other blood-pressure drugs such as beta-blockers and calcium channel blockers: Can be used together but with caution.
- Certain antifungals and antibiotics such as Ketoconazole, Itraconazole, Clarithromycin, and some antivirals: Raise the drug level in the blood, so the doctor may need to reduce the dose.
Grapefruit juice and related fruits should be avoided, because they interfere with the CYP3A4 enzyme in the liver, raising the drug level in the blood and increasing the risk of side effects such as headache, flushing, or an irregular heartbeat. Alcohol can be consumed in small amounts, but large amounts increase the risk of a drop in blood pressure and dizziness.
For safety, always tell your doctor and pharmacist about your regular medications, vitamins, and supplements, because the list of drugs that interact with Tadalafil is longer than those noted above.
Who Should Not Use Tadalafil
People taking nitrates for heart disease absolutely must not use Tadalafil, because using them together can cause a severe, life-threatening drop in blood pressure. In addition, people with heart disease, abnormal blood pressure, or severe liver or kidney disease should always be assessed by a doctor first.
“Before prescribing this class of drug, the doctor always assesses heart health and the medications the patient is taking — especially nitrate heart medications — because using them together risks a sudden drop in blood pressure. Buying medication to take on your own is therefore something to avoid.” — Physician
Groups requiring special caution include those taking alpha-blocker blood-pressure drugs, those who have had a heart attack or stroke within the past 6 months, those with low blood pressure, and those with heart conditions for which sexual activity is inadvisable. All of these must give the doctor a complete history of their medications and underlying conditions.
Tadalafil is a medication for men only; it is not used in women and children, and it must be prescribed by a doctor. Do not buy it to use on your own or take it secondhand from others, because dosage and safety differ from person to person.
Preparing Before Consulting a Doctor About Tadalafil
Preparing before seeing a doctor helps you receive more precise and safer treatment. Things to prepare include a complete list of your regular medications and supplements, your history of underlying conditions — especially heart disease, blood pressure, and diabetes — and any history of drug allergies.
You should tell the doctor frankly about your symptoms, such as how long you have had them, whether they happen every time or only sometimes, and whether stress or relationship problems are involved. This information helps the doctor distinguish whether the cause is physical or psychological.
Consulting a specialist physician at a clinic that emphasizes privacy makes it easier to talk comfortably. Those concerned about confidentiality can choose a clinic that offers private service, to reduce any awkwardness in describing symptoms.
Is There a Difference Between Generic and Brand-Name Tadalafil?
Tadalafil comes in both an original (brand, such as Cialis) and a generic form that use the same active ingredient. Generics registered with the FDA have drug-quality and effectiveness standards equivalent to the original, but are usually cheaper, making them a cost-effective option.
The important thing is to choose a drug that is properly registered with the FDA and to buy it from a licensed healthcare facility or pharmacy. Drugs sold through unreliable online sources, or drugs without a registration number, may be counterfeit with an active ingredient that does not match the label, and may be dangerous.
Store the medication in a dry place at room temperature, away from sunlight and humidity, keep it out of reach of children, and do not use expired medication. If you are unsure about storage or the expiry date, you can ask a doctor.
Conclusion
Tadalafil is a medication for erectile dysfunction whose standout feature is a long duration of action — up to 36 hours — helping couples’ lives feel more natural. Besides treating ED, it is also used to relieve the symptoms of an enlarged prostate. However, this medication must be prescribed by a doctor and has several precautions, especially in those with heart disease or those taking nitrates.
ED is a treatable condition, and it is more common than people think. Having the courage to consult a doctor is an important first step. A specialist physician will help assess overall health, find the true cause, and choose an approach suited to each individual.
PSK Clinic, a sexual-health clinic in the Lat Phrao area of Bangkok, is a healthcare facility that provides sexual-health care. Those who would like more information can contact us via LINE: @pskclinic or call 095-049-4142 during business hours.
References
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