Tadalafil: Interactions, Side Effects, Dosage, Uses and More

April 20, 2021

4 mins

For nearly two decades, one of the most common and popular methods of treating erectile dysfunction has been the prescription medication known as Cialis®. The active ingredient in Cialis® is tadalafil, which is also the generic and chemical name for this brand name ED treatment.

While the most popular – and even ubiquitous –name in treating erectile dysfunction remains Viagra® (sildenafil), there has been a rising growth of popularity over the years for tadalafil in both brand name Cialis® and the generic version. That’s due largely to two features of this particular medication: it’s long-lasting effects and the availability of a once-daily low dose for men who want to be ready for intimacy at any time.

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What is Tadalafil Used for? 

Tadalafil is a prescription medication that’s primarily used to treat erectile dysfunction, but it can also be effective in treating the symptoms of benign prostatic hyperplasia. Tadalafil is taken as a single, oral tablet, and it belongs to a group of medications called phosphodiesterase 5 (PDE5) inhibitors. Other medications found in this category include: Viagra® (sildenafil), Levitra® (vardenafil), and Stendra® (avanafil).  

In combination with sexual stimulation and arousal, PDE5 inhibitors work by increasing the blood flow to the penis in order to help a man to achieve and maintain an erection. Tadalafil can also be used to help relieve the symptoms of benign prostatic hyperplasia, such as difficulty in beginning the flow of urine, a weak stream, and the need to urinate frequently or urgently. The way it works is by helping to relax the smooth muscles found in the prostate, bladder, and penis which can increase blood flow and urine flow. PDE5 inhibitors essentially release the body’s braking mechanism for erections.

What are the Doses of Tadalafil? 

One of the largest reasons for the growing popularity of tadalafil is its versatility. Unlike other prescription medications for erectile dysfunction, tadalafil can be taken daily in a low dose. The other PDE5 inhibitors are only prescribed to be taken “on-demand” and within an hour or two of sexual activity. Tadalafil can be taken this way as well in doses of 5, 10 and 10 mg, but it can also be taken daily in lower doses of 2.5 and 5 mg. The available doses of tadalafil are 2.5 mg, 5 mg, 10 mg, and 20 mg. 

The dose that is prescribed will vary depending on a few factors such as:

• Age

• Type and severity of the condition being treated

• Other medical conditions that could impact its effectiveness

• How often the treatment will be taken

Typically, a doctor will start their patient on a lower dose and readjust over time, if necessary, to find the perfect dose. Any history of issues with the liver or kidneys may result in the doctor starting with the lowest dose of tadalafil. 

Tadalafil Taken “On Demand” 

In the event that a doctor prescribes tadalafil “on demand,” then the typical starting dosage is often 10 mg to be taken around an hour before sexual activity. This may be reduced to 5 mg if the medication is working too well or increased to 20 mg if the effects are not satisfactory. This process can take some trial and error, but a good physician will understand this process and can facilitate easy changes.

The maximum dosage of tadalafil is 20 mg in a single day, and no more should be taken in any 24 hour period. Tadalafil will stay in the body for up to 36 hours, and taking too much can create some potential health issues. Taking too much tadalafil in a single day may result in a severely decreased blood pressure.

Many men find tadalafil to be an attractive option for treating erectile dysfunction because its effects can last for 36 hours. Compared to sildenafil, the active ingredient in Viagra®, with a window for intimacy of about 4 hours, on-demand tadalafil offers considerably more flexibility.

Tadalafil Taken Daily 

Unlike other medications for erectile dysfunction, tadalafil can be used daily at a lower dose. In this case, the tadalafil dosage will typically start at 2.5 mg per day. If this isn’t enough to meet expectations, then the dosage may be increased to 5 mg, though this is the limit for once-daily use.

The benefit of once-daily low-dose tadalafil is that it allows for sporadic intimacy without any planning in the day or hours preceding. This an also benefit men with an active sex life who anticipate intimacy more than 2 or 3 times weekly.

One of the recommendations is for tadalafil daily to be taken at roughly the same time each day. The effects of tadalafil will last between 24 and 36 hours, so anytime during that window it can be effective. Missing a daily dose of tadalafil is okay, but it’s important not to take two doses in one day. 

Tadalafil to Treat Benign Prostatic Hyperplasia 

In order to treat the symptoms of benign prostatic hyperplasia, the recommended dosage of tadalafil is 5 mg taken once a day. In some cases, it may be necessary to take finasteride (Proscar) along with this medication. Both have been approved for over a decade with deep physician experience.

What are the Side Effects of Tadalafil? 

Tadalafil can cause mild or serious side effects depending on a variety of risk factors and conditions. There can be many reasons for side effects to occur, and they may be an indication of a more serious underlying medical condition. 

Some of the mild potential side effects include:

• Headache (between 3% and 15% of study participants reported headaches, compared to 2.3% and 5% of those receiving a placebo)

• Heartburn (between 1% to 10% reported this effect, vs. 0.2% to 2% on placebo)

• Back pain (between 2% and 6% reported back pain, vs. 1% to 3% on placebo)

• Muscle pain

• Stuffy nose

• Flushing in the face or body

• Pain in arms or legs

• Abdominal pain

• Indigestion 

• Nasal congestion

Typically these side effects go away within a few days or a couple of weeks, at most. However, if they become more severe or aren’t going away then it’s best to talk with a doctor or pharmacist about these side effects. The following are possible serious effects with tadalafil, but they are fairly uncommon. 

If you experience any of the following, you should call your doctor right away or may need to call 911 if you think you’re experiencing  an emergency situation.

Changes in Hearing 

Some of symptoms may include: trouble hearing, hearing loss, ringing in your ears, or dizziness.

Allergic Reaction 

It’s possible to experience an allergic reaction after taking tadalafil. While allergic reactions occurred during clinical trials of Cialis®, the precise statistics on allergic reactions aren’t available.

Some symptoms of an allergic reaction include:

• Skin rash

• Itchiness

• Flushing

• Swelling under the skin, eyelids, lips, hands, or feet

• Swelling of the tongue, mouth, or throat

• Difficulty breathing

Changes In Blood Pressure 

Low blood pressure is one of the more common side effects when taking tadalafil, but high blood pressure can be a result as well. Clinical trials monitored blood pressure in people that took 20 mg of tadalafil and people that took a placebo. They found that blood pressure for those taking tadalafil decreased by an average of 1.6/0.8 mm Hg more in the tadalafil group than the placebo group. 

A decrease in blood pressure is more likely when tadalafil is combined with other medications that can lower blood pressure. Symptoms of low blood pressure can include:

• Dizziness

• Blurry vision

• Fainting

Although rare, tadalafil can also increase blood pressure. This side effect was only reported in people that took tadalafil once a day. Only 1% to 3% of the people reported high blood pressure, and no placebo was given during the study. Symptoms of high blood pressure may include:

• Headaches

• Chest pain

Prolonged Erection 

It’s possible to have an erection that lasts longer than four hours when taking tadalafil. This side effect is also known as priapism, and can cause permanent damage to the penis that could result in losing the ability to achieve erections at all. 

Loss of Vision 

Very rarely, tadalafil may cause the loss of vision in one or both eyes. 

Interactions With Other Drugs 

Tadalafil can interact negatively with other medications and even certain foods. Different interactions can cause varying effects. For example, some interactions may only impact the effectiveness of the drug, while others may increase the number of side effects or make them more severe. 

These are a list of other medications that should not be taken when using tadalafil:

• Nitrates such as nitroglycerin, isosorbide mononitrate (Monoket), or isosorbide dinitrate (Isordil)

• Alpha blockers such as tamsulosin (Flomax), alfuzosin (Uroxatral), or doxazosin (Cardura)

• Medications that lower blood pressure such as amlodipine (Norvasc), metoprolol (Toprol XL, Lopressor), or enalapril (Vasotec)

• Medications that treat heartburn such as calcium carbonate (Tums) or aluminum hydroxide/magnesium hydroxide (Mylanta)

• CYP3A4 inhibitors such as ketoconazole, itraconazole (Sporanox), erythromycin (Ery-Tab), ritonavir (Norvir)

• CYP3A4 inducers such as rifampin (Rifadin), carbamazepine (Tegretol), phenytoin (Dilantin), or phenobarbital 

• Guanylate cyclase stimulators

In addition to these medications, it’s best to avoid alcohol and grapefruit as well. 

Alcohol and tadalafil can both decrease blood pressure, so drinking while taking tadalafil could create some serious issues. A drink or two is okay, but moderate to excessive  drinking can be dangerous. 

In addition, eating grapefruit or drinking grapefruit juice can block the enzyme CYP3A4in the body. This enzyme is breaks down tadalafil in your liver, so if it’s abilities are altered it may result in too much tadalafil in your system.

How Rex MD Can Help

Tadalafil is one of the most popular treatments for erectile dysfunction. It’s considered as effective as any other PDE5 inhibitor, and with similar side effects. The option to take tadalafil daily or “on demand” has helped make it a popular choice in men looking for erectile dysfunction relief. 

One of the biggest concerts about tadalafil can be price. Cialis® is often one of the more expensive brands of erectile dysfunction, as it stays in the body longest and has the option of being taken daily. The generic version of tadalafil is much cheaper, and the licensed physicians at Rex MD can help you navigate the complexities of ED treatment - all from your phone or computer.