Cialis (tadalafil) is an oral treatment for erectile dysfunction that increases blood flow to the penis when sexual stimulation is present. It is also used for the symptoms of benign prostatic hyperplasia. The most serious risk is that it must not be taken with nitrates used for angina, because blood pressure can drop severely. See your doctor before your first tablet, since erectile dysfunction can reveal a heart problem or diabetes.
What is Cialis and why is it prescribed?
Cialis is the brand name for the active ingredient tadalafil, which belongs to a group of drugs called phosphodiesterase (PDE) inhibitors. In erectile dysfunction, it works by increasing blood flow to the penis during sexual stimulation, which allows an erection to occur [1]. You can find more detail in the Cialis drug entry in our drug directory and in the tadalafil (Cialis) glossary entry.
Tadalafil is not used only for erectile dysfunction. It is also prescribed for the symptoms of benign prostatic hyperplasia in adult men, such as weak urine flow, frequent urination and urgency [1]. It may also be given for pulmonary arterial hypertension under another product named Adcirca, but the two products must not be combined. Treatment should use only one of them at a time [1]. If you have prostate symptoms along with sexual dysfunction, read our article on benign prostatic hyperplasia.
It is important to know the limits of this drug. It does not cure erectile dysfunction and does not increase sexual desire. It also does not prevent pregnancy or the transmission of sexually transmitted infections such as human immunodeficiency virus (HIV) [1].
Why should you see a doctor before your first tablet?
Erectile dysfunction is common and becomes more frequent with age, but it is not a normal part of aging [3]. It can be a sign of another health problem. It may mean blocked blood vessels or nerve damage caused by diabetes [3]. If you do not see a doctor, these problems may remain untreated [3].
For this reason, medical authorities recommend a doctor's examination even if you obtain the medication from a pharmacy on the pharmacist's advice. The UK National Health Service (NHS) advises that anyone buying tadalafil without a prescription have a doctor's check-up within 6 months of starting it, because erectile problems may indicate diabetes or heart disease [2]. To learn more about this link, read our article Erectile dysfunction: when is it an early warning of arterial disease?.
What should you tell your doctor?
- All your medications, prescribed and non-prescribed, along with vitamins and herbs, especially any medicine for angina or for prostate enlargement [1].
- Your illnesses: diabetes, high or low blood pressure, high cholesterol, heart rhythm disorders, heart attack, heart failure, stroke, and kidney or liver disease [1].
- If a doctor has previously advised you to avoid sexual activity for a medical reason, or if you have felt chest pain during intercourse [1].
- If you have had an erection lasting more than 4 hours, sudden loss of vision, an inherited retinal disease, or if you smoke [1].
Sexual activity places a strain on the heart, especially for those with heart disease [1]. For this reason, the heart's ability to tolerate physical exertion is assessed first, to determine whether it can cope with sexual activity. The cause may be psychological or mixed, and sometimes lifestyle changes help: exercise, weight loss and quitting smoking [3]. You can read male sexual problems to understand the wider picture.
Why is Cialis prohibited with angina medicines (nitrates)?
Nitrates are drugs that widen blood vessels and are used for chest pain (angina pectoris). Tadalafil also widens blood vessels, so if the two are combined, blood pressure may fall severely. For this reason, our drug reference states that nitrates in all their forms are absolutely contraindicated with tadalafil, and that this drop may be fatal. Because its effect lasts a long time, nitrates should not be given even 48 hours after the last dose. Reliable medical sources confirm the same warning: MedlinePlus noted that the doctor will often advise against using tadalafil for those taking nitrates [1], and the NHS stated that it is not usually prescribed with them [2].
What are nitrates?
- Examples of medicines: isosorbide dinitrate, isosorbide mononitrate, and nitroglycerin (also called GTN) [1][2].
- Forms: tablets, sublingual (under-the-tongue) tablets, sprays, patches and ointments [1].
- Other substances containing nitrates: "poppers" such as amyl nitrite, which are recreational substances that doctors warn against using with tadalafil [1]. Illegal drugs such as amphetamine, ecstasy and cocaine increase the risk of serious side effects [2].
- The drug riociguat, used for lung diseases, must also be reported to your doctor [1].
What should you do in practice?
- If you use an angina medicine and do not know whether it contains nitrates, ask your doctor or pharmacist before taking any tablet [1].
- Do not stop or change your heart medicine on your own in order to use Cialis. The decision belongs to your doctor, who may choose a suitable alternative for your condition.
- Tell everyone treating you that you take tadalafil. If you need emergency treatment for a heart problem, the team will need to know when your last dose was taken [1].
- If chest pain or severe dizziness appears after taking it, call 911 or go to the nearest emergency department.
Dizziness on standing is a symptom that may worsen with blood pressure medicines and dehydration. You can read an explanation in our article on postural hypotension.
What other drug interactions should you be aware of?
Nitrates are the most dangerous interactions, but they are not the only ones. The following table shows common groups. It is for awareness only, as your doctor and pharmacist decide what suits your condition.
| Group | Examples | What you should know |
|---|---|---|
| Alpha blockers (for prostate enlargement and blood pressure) | Tamsulosin (Flomax), doxazosin, alfuzosin [1] | Additive blood pressure drop may occur. Combining them is familiar but is done under medical direction: the doctor starts with the lowest doses and with a time gap between them. |
| Blood pressure medicines and some heart medicines | Amlodipine not mentioned; listed: diltiazem, verapamil, amiodarone [1] | Tell your doctor about them, as they may adjust the doses or monitor you closely [1]. |
| Antifungals | Fluconazole, itraconazole, ketoconazole [1] | They may change the level of the drug in the body and require monitoring [1]. According to our drug reference, they raise its level. |
| Antibiotics | Clarithromycin, erythromycin, rifampicin [2] | They may not be compatible with tadalafil, and your doctor must be told about them [2]. |
| Epilepsy and HIV medicines | Carbamazepine, phenytoin, phenobarbital, and HIV protease inhibitors [1] | Doses may need to be adjusted [1]. |
| Other erectile dysfunction medicines | Sildenafil (Viagra), vardenafil (Levitra) [1] | Do not combine two erectile dysfunction medicines except on a doctor's instructions [1]. |
| Herbs and foods | St. John's wort, grapefruit juice [1] | Tell your doctor about herbs. The NHS advises not drinking grapefruit juice during treatment [2]. |
For this reason, experts recommend carrying a written list of all the medicines, vitamins and supplements you take, and showing it at every visit to the doctor or emergency department [1].
How is Cialis used safely?
Correct use starts with the prescription and the instructions of your doctor or pharmacist. The usual dose set by the doctor for erectile dysfunction is 10–20 mg as needed, or 5 mg daily, and it may vary depending on your condition and medications. Do not adjust the dose on your own.
Two ways of using it
- As needed: usually taken at least 30 minutes before sexual activity, and no more than once every 24 hours [1]. The NHS states that its effect may last up to 36 hours, so no more than one tablet should be taken per day [2].
- Daily: taken every day at about the same time, and intercourse may be attempted at any time between doses [1]. The daily dose takes about a week to reach a steady level, so do not judge it from the first night.
The tablet is swallowed whole with water and may be taken with or without food [1][2]. Your doctor may start with a moderate dose and then increase or decrease it depending on your response, so tell them if it does not work well or causes symptoms [1].
Points that matter for your safety
- Missing a daily dose: take it when you remember, unless the next dose is due soon, in which case skip it. Do not double the dose [1][2].
- Overdose: taking an extra dose may be dangerous [2]. Call your doctor or go to emergency with the medicine box, and do not drive yourself if you feel unwell.
- Alcohol: excessive drinking may cause dizziness, headache, palpitations and a drop in blood pressure [1]. The NHS notes that excessive drinking also makes erection harder to achieve [2].
- Dehydration: tell your doctor if you have recently had diarrhea, vomiting, heavy sweating or have been drinking too little fluid [1].
- Surgery: tell the surgeon or dentist that you are taking the medicine [1].
- Storage and sharing: keep it out of reach of children and at room temperature, away from moisture [1]. Never give your medicine to anyone, as each person needs their own assessment. Read the answer to the question Can I use a prescription medication prescribed for another family member?.
For general rules on safe medication use, see the consumer guide to medication safety.
What are its common side effects?
Like other medicines, tadalafil may cause side effects, most of which are mild and temporary. Not everyone who takes it experiences them [2].
| Symptom | Notes |
|---|---|
| Headache and facial flushing | Among the most common symptoms [2]. According to our drug reference, these are usually milder than with Viagra. |
| Indigestion and heartburn | Common [1][2]. |
| Nasal congestion | Common [2]. |
| Back, muscle, arm and leg pain | One of the most characteristic effects [2]. It usually appears after 12–24 hours and goes away within days, according to our drug reference. |
| Dizziness | May occur. If you feel it, wait until it passes before driving [2]. |
If these symptoms bother you or persist, speak to your pharmacist or doctor, who may suggest ways to relieve them [2]. If you take painkillers for back or muscle pain, first review safe use of pain relievers.
When should you go to emergency and when should you see a doctor?
Call 911 or go to the nearest emergency department if:
- An erection lasts more than 4 hours, especially if it is painful, as this is an emergency because it threatens penile tissue [1][2].
- Chest pain, noticeable palpitations or shortness of breath appear [1][2].
- You lose vision or your vision suddenly weakens, or your color vision changes (such as a blue tint on objects) [1].
- Signs of an allergy appear: hives or rash, swelling of the face, throat, tongue or lips, difficulty breathing or swallowing, or peeling skin [1][2]. For more on this condition, read the page on drug allergy.
- A seizure occurs [2].
If you suddenly lose vision, or experience a sudden loss of hearing (possibly with ringing in the ears or vertigo), stop taking further doses of tadalafil or similar medicines, and do not resume it before speaking to a doctor [1]. Vision loss has been reported as permanent in some cases, and it has not been established whether the drug is the cause [1].
See your doctor soon if:
- You feel chest pain, dizziness or nausea during sexual activity. Contact your doctor immediately or request emergency care, and avoid sexual activity until your doctor allows it [1].
- The medicine has not provided the expected benefit or has caused bothersome symptoms [1].
- You have started a new medicine that may interact with it.
How do you buy Cialis safely in Jordan?
The Jordan Food and Drug Administration (JFDA) regulates medicines and their public prices in Jordan. For this reason, buy your medicine only from a licensed pharmacy, with a doctor's prescription or on the pharmacist's advice, and make sure the package is sealed, intact and contains the leaflet.
- Avoid tablets sold through unknown websites or pages, or by people who are not pharmacists, as you cannot verify their contents or how they were stored.
- Be wary of "herbal enhancers" and quick-marketed products, as they may interact with your medicines. It is useful to read risks of herbal supplements for psychogenic erectile dysfunction.
- Tell the pharmacist about all your medicines, especially heart and prostate medicines, before you take the package [1].
- Do not be embarrassed to ask. Honesty with your doctor and pharmacist is what makes a prescription safe, and it may help you avoid a dangerous interaction.
How do you find the right doctor in Jordan?
The specialty closest to your problem is urology, and you can browse urologists in Jordan. If you have heart disease, high blood pressure or diabetes, the doctor may request an assessment with a cardiologist or internist before prescribing. You can narrow your search by governorate, such as urology in Amman, urology in Irbid or urology in Zarqa, and pages for the other governorates are available from the specialty page. You can also find a description of the condition on the erectile dysfunction page.
What should you check in a doctor's profile?
- The specialty and qualifications listed in the profile.
- The clinic location and working hours, and whether the profile allows contact or booking.
- The services the clinic offers, and whether they include assessment of sexual dysfunction or prostate disease.
Questions to ask at the appointment
- Could my erectile dysfunction be a sign of heart disease or diabetes, and what tests are needed?
- Are my current medicines, especially heart and prostate medicines, safe with tadalafil?
- Is the as-needed dose or the daily dose more suitable for me, and when should I expect a result?
- What symptoms require emergency care? Is there a non-drug treatment suitable for me?
ClinicsJo does not rank doctors by their medical quality, and does not provide online consultations or prescriptions. Its role is to help you reach the right doctor, and your clinical assessment takes place with the doctor.
Quick summary before you take a tablet
- Cialis is effective for many men, but it is not a curative treatment and does not increase desire [1].
- Nitrates in all forms are prohibited with it, and do not change your heart medicine on your own.
- Erectile dysfunction may signal heart disease and diabetes, so use it as an entry point for a comprehensive check-up [3].
- An erection lasting more than 4 hours, chest pain, and sudden loss of vision or hearing are immediate emergencies [1].
- Buy from a licensed pharmacy, and be honest with your doctor.
This article is for health education and does not replace consulting a doctor or pharmacist.
Frequently asked questions
Can Cialis be used with sublingual angina medicine?
No. Angina medicines in the nitrate class, including sublingual nitroglycerin tablets, are prohibited with tadalafil because combining them may cause a severe drop in blood pressure. Tell your doctor about all your medicines before your first tablet, and do not stop or change your heart medicine on your own. If you feel chest pain or severe dizziness, call 911.
How many hours must I wait after Cialis before taking nitrates?
Tadalafil's effect lasts a long time in the body, so according to our drug reference, nitrates should not be given until at least 48 hours after the last dose. If you need emergency treatment for chest pain, tell the medical team immediately when your last tablet was taken, because this determines which medicine they can safely use.
Does Cialis cause back and muscle pain?
Yes, back, muscle, arm and leg pain is a common symptom. It usually appears about 12 to 24 hours after a dose and typically goes away within days. If the pain is severe, persistent or accompanied by other symptoms, see your doctor or pharmacist, and do not take additional painkillers without consulting them.
Can erectile dysfunction indicate a heart problem?
It can. Erectile dysfunction is sometimes linked to blocked blood vessels or nerve damage caused by diabetes, so it is not advisable to take a tablet without an examination. The doctor will assess your heart, blood pressure, blood sugar and cholesterol, and decide the appropriate plan for you. Early detection protects both your heart and your sexual health.
What should I do if an erection lasts more than 4 hours?
This is a medical emergency. Go immediately to the nearest emergency department or call 911, and do not wait for it to resolve on its own, as a prolonged erection may damage penile tissue. Do not take any additional dose, and tell the medical team the name of the medicine, the time you took it and any other medicines you use.
Is it safe to drink alcohol or grapefruit juice with Cialis?
Excessive alcohol may cause dizziness, a drop in blood pressure and reduced sexual performance, so moderation or avoidance is preferable, according to your doctor's advice. Grapefruit juice may raise the level of the drug in the body, and medical references recommend avoiding it or discussing it with your doctor or pharmacist.
Sources and references
- Tadalafil: MedlinePlus Drug Information — MedlinePlus — U.S. National Library of Medicine. Accessed: 2026-10-26.
- Tadalafil — NHS (UK National Health Service). Accessed: 2026-10-26.
- Erectile Dysfunction | ED | Impotence — MedlinePlus — U.S. National Library of Medicine. Accessed: 2026-10-26.
