Medically reviewed by: Thomas Fischer (Pharmacist). This article has been written according to strict guidelines and medical standards.
Medically reviewed by: Thomas Fischer (Pharmacist)
Tadalafil, better known by its brand name, Cialis, is a very popular treatment for erectile dysfunction. The product has been on the market for around 30 years; a lot of studies have been conducted on it. As such, there is a load of scientific information available about it.
Like all medications, tadalafil has some side effects. For most users, they are minor and generally disappear in a few days. Yet for others, they can be a lot more dangerous. People react to medications in different ways; for some people, the side effects are more severe than for others.
Before deciding to take any form of medication, it is worth knowing what side effects are likely. This can help you choose whether the benefit outweighs the risks. Always discuss these facts with a medical professional before going ahead with this type of pharmaceutical drug.
The Most Common Side Effects of Tadalafil (Cialis)
Tadalafil is a PDE5 inhibitor. It prevents the PDE5 enzyme from attacking the cGMP enzyme, which is what relaxes muscle layers. As this medication affects the bloodstream, most side effects will come from blood or muscle areas.
The following side effects are common for many users of tadalafil, to various degrees. Over time as the body adjusts to the medication, these tend to fade. Lowering the dose also appears to assist in relieving these side effects.
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Headaches
In almost every study, tadalafil users site headaches as the most common side effect. This is most likely the result of it being a vasodilator. As a person’s blood vessels dilate, this can put some pressure on the nerves in the side of their head, generating headaches.
Flushing
Another side effect that appears to be quite common is facial flushing. Many first-time users report a feeling of heat in their faces, possibly including a small amount of redness. This is often a one-time occurrence for the first consumption of the pill and disappears rather quickly.
Heartburn
Indigestion or heartburn are some other common side effects. Tadalafil can relax your lower esophageal sphincter, causing your stomach acid to travel from your stomach upwards into your esophagus. This can create a feeling of heartburn. Drinking more water when taking medicine can assist with the relief of this.
Back Pain
Around 5% of users report back pain as a side effect. This usually appears about 12-18 hours after taking the tablet and fades once the results of the medicine have left the body. Most of the time, this is mild pain and can be treated with over-the-counter painkillers.
Uncommon Side Effects of Tadalafil (Cialis)
The following side effects are much less common and have been reported in less than 2% of people taking tadalafil.
Nasal Congestion
Most likely linked to nitric oxide, which tadalafil allows to operate freely, the nasal passages can feel stuffy or blocked. Breathing through the nose can feel challenging. This tends to fade rapidly as the body adjusts to the medication.
Dizziness
As blood is flowing more freely around the body during the period when tadalafil is taken, low blood pressure symptoms can occur. The most common of these is a feeling of light-headedness, or fainting, especially when standing up. Taking it slowly when moving to an upright position will help this not to happen. Adjusting the dose tends to reduce this problem.
Heart Conditions
People with existing heart conditions need to be careful when taking Cialis as it could interact with it. Any lowering of blood pressure could result in hypertension, or worse, cardiac arrest. Discuss with a doctor any medications you are already taking before even considering using any form of ED medication.
What Are Rare Side Effects of Tadalafil (Cialis)?
While rare, these issues are particularly dangerous, and physicians warn users to cease taking the medication immediately and seek hospital care.
Hearing Issues
It appears that tadalafil as a PDE5 inhibitor can cause hearing loss. It’s sporadic and has only been reported by a minimal number of users. It is usually accompanied by tinnitus (a ringing sound in the ears), and dizziness.
Psychological
Once again, only a very few numbers of users have reported minor psychological behavior changes like confusion, nervousness, and short-term memory problems.
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Tadalafil (Cialis) Side Effects With the Eyes
Tadalafil as a PDE5 inhibitor has been linked to issues with the eyes. There are several common and less serious side effects, and one considerably more concerning.
Common and Less Serious
Some users of Cialis experience mild forms of blurred vision, a blue tinge around their image, or impaired colors. These side effects generally last only while the medication is in the body and rapidly disappears as it does.
As tadalafil remains in the persons’ body longer than other ED medications, these symptoms can continue for a few hours. Doctors will often recommend a lower dosage or switching to a product with less retention time.
Uncommon Yet Very Serious
The one side effect that causes some concern for medical professionals and has been linked to Cialis (along with 5 other PDE5 inhibitors) is nonarteritic anterior ischemic optic neuropathy, also known as NAION.
Damage to the optic nerve is a rare side effect and is linked to other factors. Usually found in patients over 50 years of age, often already diagnosed with hypertension or diabetes, and with an existing condition known as a small cup to disc ratio.
The optic disc is the region in which the optic nerve attaches to the back of the eye, and the optic cup is a smaller circular region within the disc. If the cup is too small, then the supply of blood to the optic nerve is restricted.
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Tadalafil (Cialis) and Priapism
Finally, a less common but equally concerning side effect of taking tadalafil is priapism. Simply put, this is an erection that doesn’t go away for many hours. It’s not as great as it sounds; it is painful and can cause severe irreversible damage if it’s not treated immediately.
The Two Types of Priapism
There are two types of priapism, ischemic and nonischemic, and symptoms vary between the two.
Ischemic Priapism
Also known as low-flow priapism, this is where blood flow is restricted from the penis. Of the two types, this is the most common. The symptoms are an erection lasting more than four hours and unrelated to sexual interest or stimulation, including constant and increasing penile pain. Another sign is a rigid penile shaft, but the tip (glans) is soft. Ischemic priapism requires immediate medical assistance.
Nonischemic Priapism
Less common, nonischemic is the opposite and called high-flow, where the blood flow isn’t regulated. The symptoms here are also a long-lasting erection without sexual interest and an erect but not sufficiently rigid penile shaft. Doctors will often advise patients to let the body fix nonischemic itself, under medical supervision.
Tadalafil (Cialis) and Priapism - Other Factors
Tadalafil use may not be the main contributor to priapism but does assist in its occurrence. Patients found to be suffering from Sickle Cell Anemia are often prone to this affliction. This illness causes abnormally shaped red blood cells; these, in turn, can block the blood vessels in the penis.
Cocaine, marijuana and other illicit drugs have been known to cause ischemic priapism, so avoid taking those if you are using tadalafil.
When To Get Help
If the penis remains erect and in pain for 4 or more hours, seek medical assistance. If left untreated, there could be tissue damage inside the penis that could increase further already existing erectile dysfunction.
Treating ischemic priapism isn’t a pleasant experience; it usually involves draining the blood from the penis using a needle and syringe. Alternatively, a drug like phenylephrine is injected into the penis. This opens the blood vessels and assists the blood draining away.
Not to Be Confused With…
Cialis can remain in the body for up to 36 hours. During this time, any forms of sexual stimulation, including visual, could result in an erection, wanted or otherwise. Erections that come and go like this are quite typical for tadalafil users and are not the same as priapism, where the penis remains erect, non-stop, for 4 hours or more.
Article Sources
- Questions and Answers for Cialis (tadalafil). In: U.S. Food and Drug Administration. URL: https://www.fda.gov/
- Parker-Pope, Tara (August 28, 2009). “The Cost of Treating Erectile Dysfunction“. New York Times.
- CIALIS- tadalafil tablet, film coated. Eli Lilly and Company. URL: https://uspl.lilly.com/
- A Study of Tadalafil and Sildenafil in Men With Erectile Dysfunction in China. Information provided by (Responsible Party): Eli Lilly and Company. URL: https://clinicaltrials.gov/ct2/show/NCT01352507
- Porst, Hartmut et al. Efficacy of tadalafil for the treatment of erectile dysfunction at 24 and 36 hours after dosing: a randomized controlled trial. In: Urology Volume 62, 07/2003. Elsevier Inc.
- Brock, Gerald et al. Efficacy and Safety of Tadalafil for the Treatment of Erectile Dysfunction: Results of Integrated Analyses. In: The Journal of Urology Volume 168, 10/2002. Elsevier Inc.
- Eli Lilly and Company Limited (2017). Cialis 20mg film-coated tablets. EMC. [online] Available at: https://www.medicines.org.uk/emc/files/pil.7430.pdf [accessed 20th July, 2020].
- Moncada, I., Bethencourt, F, R and Lledó-García et al., (2014). Effects of Tadalafil Once Daily or On Demand Versus Placebo on Time to Recovery of Erectile Function in Patients After Bilateral Nerve-Sparing Radical Prostatectomy. World J Urol: 33, pp 1031-1038.