A Complete Guide To Cialis (Tadalafil) Side Effects

A Complete Guide To Cialis (Tadalafil) Side Effects
14 November, 2023

Erectile dysfunction, or ED, is one of the most common male sexual performance issues, affecting up to 40 percent of all men by the age of forty.

Cialis is an FDA-approved medication that’s designed to treat erectile dysfunction. It’s the longest-lasting erectile dysfunction medication on the market, providing effects that can last for up to 36 hours (Viagra, in comparison, usually lasts for three to five hours).

Like other erectile dysfunction drugs, Cialis is a PDE5 inhibitor. It works by increasing the flow of blood to the erectile tissue of your penis. When you’re sexually aroused, this makes it easier to get and keep an erection.

Cialis is a safe, effective medication. It’s prescribed to more than one million men in the United States alone, with many more users internationally.

However, like any other prescription medication, Cialis can have side effects. Most of these are fairly minor, although it’s possible for Cialis and other PDE5 inhibitors to cause a range of more severe side effects in some cases.

Below, we’ve listed the common and uncommon side effects of tadalafil, the active ingredient that’s used in Cialis. For side effects with study data available, we’ve also provided information on how frequently they occur and what you can do to mitigate or avoid them.

The Most Common Side Effects of Cialis

Cialis has several common side effects. Many of these side effects also occur with other drugs used to treat erectile dysfunction. This means that if you experience a certain side effect while using Cialis, you might also experience it from drugs like Viagra or Levitra.

Overall, minor side effects from Cialis are fairly common. In fact, in a 2004 study of 2102 men who used Cialis, 51 percent reported experiencing one or more common, typically minor side effects from the medication.


Headaches are a common side effect of all ED medications, including Cialis. In fact, headaches are the most frequently reported side effects of Cialis, making an appearance in almost all trials of the medication.

Cialis is a vasodilator. This allows it to improve blood flow to specific areas of your body, such as the erectile tissue of your penis. By making your blood vessels dilate, Cialis can put pressure on the nerves in the side of your head, increasing your risk of developing a headache.

Most of the time, headaches from Cialis are fairly mild. They typically become less intense over time, although Cialis’s long half-life means that a dull headache can last for several hours after using the medication.

According to a 2008 review of studies of tadalafil (the active ingredient in Cialis), 15 percent of men who use Cialis at the highest recommended dose of 20mg experience headaches. At a lower 10mg dose, headaches are still common, affecting about 12 percent of Cialis users.

If you’re prone to headaches from Cialis, our guide to dealing with headaches from ED drugs can help. It lists several techniques for managing this side effect, from lowering your dosage of Cialis to using over-the-counter pain relief.


Cialis can cause a range of digestive issues, including indigestion/heartburn. This is one of the most common side effects of Cialis, affecting about 8 percent of users at the maximum 20mg dosage and 7 percent of users at a lower 10mg dose.

Indigestion/heartburn is a common side effect of all ED medications, not only Cialis. It occurs as a result of Cialis’s action on smooth muscle tissue in your body. As well as targeting the smooth muscle tissue in your penis, Cialis can also affect other tissue throughout your body.

When you take Cialis, it can cause your lower oesophageal sphincter, which controls the flow of your stomach contents, to relax. This can lead to heartburn as stomach acid travels from your stomach upwards into your oesophagus.

Most of the time, this side effect can be managed by increasing your water consumption and using over-the-counter antacids. If you experience this side effect often, it’s also worth discussing lowering your Cialis dosage with your doctor.

Finally, you should avoid drinking alcohol with Cialis, as the combination of alcohol and Cialis can increase the drug’s effects on the lower oesophageal sphincter.

Back Pain

Cialis can cause back pain. While most side effects of Cialis also occur with Viagra and Levitra, back pain appears to be significantly more common in people who use Cialis than with other ED medications.

Approximately 5 to 6 percent of Cialis users experience back pain from the medication. Back pain tends to occur about 12 to 24 hours after taking the medication. Most people who get back pain from Cialis report that it typically fades away on its own within 48 hours.

Mild to moderate back pain from Cialis can be treated using over-the-counter pain relief. If you experience uncomfortable, severe back or muscle pain after using Cialis, it’s important to talk to your doctor about adjusting your dosage or switching to another ED medication.

Muscle Aches

Like Viagra and other ED medications, a small percentage of men who use Cialis experience muscle aches. These aches are usually mild and tend to last as long as Cialis is active in your bloodstream.

About 3 to 5 percent of men who use Cialis report muscle aches as a side effect. If you experience pain after using Cialis that’s more than just a faint annoyance, it’s important to discuss this with your doctor.

Facial Flushing

Because Cialis causes your blood vessels to dilate, it can temporarily give you a red, flushed appearance. Flushing typically affects the skin around your nose, cheeks, chin and forehead, although it can also occur elsewhere on the face and body.

About 3 percent of people who use Cialis experience facial flushing. This side effect occurs at high and moderate dosages of the medication. Like other side effects of Cialis, it usually fades as your body metabolises the tadalafil in Cialis over several hours.

Since this is a common side effect of ED medications, switching to Viagra or Levitra might not be an effective way to avoid facial flushing. If you’re prone to facial flushing, it’s best to discuss this side effect with your doctor.

Nasal Congestion

Like other ED medications, Cialis can cause nasal congestion. This side effect occurs in 2 to 3 percent of men who use Cialis and can occur at both a 10mg and 20mg doses.

Nasal congestion occurs as a side effect of Cialis’s action on blood vessels. After you use Cialis, it can affect nitric oxide levels in your body’s airways, including the nasal passage. This can give you a stuffy, blocked nose that makes breathing through your nostrils difficult.

As with many other Cialis side effects, nasal congestion tends to fade away on its own as your body metabolises the tadalafil in Cialis.

While nasal congestion is a common side effect of all ED medications, switching from Cialis to shorter-acting drugs like Viagra or Levitra can make this side effect less long-lasting as a result of their shorter half-lives.

Nasopharyngitis (Cold)

Some men who use Cialis report experiencing the symptoms of a cold, or nasopharyngitis, after taking the medication. This side effect affects approximately 8 percent of men at a 10mg dose and 2 percent of men at the highest 20mg dose of tadalafil (the active ingredient in Cialis) in studies.

As the common cold is a viral infection, it’s unlikely that Cialis is directly responsible for causing people to become sick. However, the drug’s effects on the soft tissue of the nose and throat may cause some users to experience symptoms similar to those of a cold.

If you experience cold symptoms after taking Cialis, it’s most likely due to the effects of the drug on your body’s soft tissue. If these symptoms bother you, consider talking to your doctor about adjusting your dosage or switching to a shorter-acting erectile dysfunction treatment.


Dizziness is a fairly uncommon side effect of Cialis. A small percentage of men who use Cialis report feeling dizzy and lightheaded after taking the medication. These cases often involve the use of other drugs (both legal and illegal), as can be seen in some side effect reports.

Other ED medications, such as Viagra and Levitra, can cause dizziness due to their effects on nitric oxide levels. As with many other common side effects of Cialis, this can often be reduced by adjusting your dosage of the medication.

Visual Disturbances

Several ED medications, including Cialis, are linked to visual disturbances such as blue coloured vision, blurred vision and impaired colour. These side effects may occur due to the effects of the medication on the PDE-6 enzyme, which is present inside the retina.

Although these side effects are temporary, they have the potential to affect your vision while the medication is still active in your body. Because Cialis has a longer half-life than other ED drugs, this means that you could have some level of blurred vision or colour issues for several hours.

If you experience blurred vision, difficulty seeing certain colours or other visual disturbances after using Cialis, talk to your doctor. These side effects could be treatable by adjusting your dosage or using a shorter-acting medication to treat erectile dysfunction.

Reduced Blood Pressure

Like other PDE5 inhibitors, Cialis can cause a slight reduction in your blood pressure. In healthy men without heart disease or other cardiovascular conditions, this is not a problem and does not cause any health issues.

This is a common side effect of all FDA-approved medications for erectile dysfunction. It occurs as a result of Cialis’ effects as a vasodilator, which relaxes smooth muscle tissue and prompts blood vessels to dilate.

This drop in blood pressure can be potentially dangerous if you take certain medications to treat hypertension, such as nitrates. If you have any cardiovascular health issues, make sure you tell your doctor about these before you discuss Cialis or any other treatment for ED.

Less Common, More Serious Side Effects of Cialis

Cialis can cause several more serious side effects, although these are rare. Serious side effects of Cialis include priapism — a type of painful erection that can last for four hours or longer — and interactions with some medications used to treat hypertension and angina.


Priapism is a prolonged, often painful erection that lasts for four hours or longer. It’s a serious medical emergency that requires immediate attention to avoid damaging the erectile tissue of your penis.

Although it’s possible to experience priapism after using Cialis, this is an extremely rare side effect. In total, there were only 93 cases of priapism from all ED medications recorded in the entire year of 2007, of which only 16 involved men who had taken Cialis.

When you consider that more than one million men use Cialis in the US alone, the chance of experiencing priapism after using the medication is very low.

If you get a persistent, painful erection after using Cialis, it’s important to seek out emergency medical care. A qualified professional can safely and effectively treat priapism to prevent any damage to the tissue of your penis.

Damage to the Optic Nerve

Cialis is one of several ED medications that’s linked to potential damage in certain parts of the optic nerve, affecting vision. Like priapism, this is a rare side effect that only affects a tiny percentage of Cialis users.

The condition that Cialis is linked to is called nonarthritic anterior ischemic optic neuropathy, or NAION. It occurs when blood supply to the optic nerve is reduced and can potentially cause the loss of the upper or lower hemifield of the visual field in one eye.

Although exact data isn’t available, tadalafil is listed as one of several PDE5 inhibitors linked to rare post marketing reports of NAION in a study of sildenafil (Viagra) and optic nerve damage.

So far, this side effect appears to occur primarily in people with a pre-existing risk factor for eye damage, such as a small cup to disc ratio that’s associated with nonarthritic anterior ischemic optic neuropathy.  

Hearing Issues

Cialis, as well as similar ED medications such as Viagra and Levitra, may have the potential to cause hearing loss. According to the FDA, cases of hearing loss, in some cases accompanied by tinnitus and dizziness, have a “temporal association to the intake of PDE5 inhibitors.”

Like priapism and damage to the optic nerve, cases of hearing loss caused by Cialis are highly uncommon. In some cases, reports of hearing loss from Cialis and other PDE5 inhibitors were also linked to other factors that may have contributed to this side effect.

If you use Cialis to treat ED and notice any effects on your hearing, the FDA recommends that you stop taking the medication and seek prompt medical attention.

Interaction With Blood Pressure Medications

Cialis can interact with nitrates used to treat hypertension, angina and other heart conditions, causing a sudden drop in blood pressure that can lead to loss of consciousness and even cardiac arrest.

If you use nitrates such as nitroglycerin, isosorbide dinitrate, isosorbide mononitrate or amyl nitrate to treat hypertension or angina, you should not take Cialis. In fact, you should not use any PDE5 inhibitors, such as Viagra (sildenafil), Levitra (vardenafil) or Revatio (sildenafil).

All of these drugs interact with nitrates to cause a significant drop in blood pressure. In addition to nitrates used to treat cardiovascular conditions, these drugs can interact with “poppers” that contain amyl nitrate.

Do not use Cialis if you use any nitrate medications. If you have heart disease, hypertension or any other cardiovascular condition, you must inform your doctor about this and any medication you use to treat it before considering Cialis to treat erectile dysfunction.

Learn More About Cialis and Erectile Dysfunction

Although it’s quite normal to experience one or several minor side effects from Cialis, serious side effects are very uncommon. Cialis is a safe, effective medication that’s used by over one million men in the United States alone to reliably treat erectile dysfunction.

Interested in learning more about Cialis? Our guide to what you should expect from erectile dysfunction medication compares Cialis to Viagra and Levitra, with information on everything from onset of action to its half-life, cost and effects on sexual performance.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.