Tadalafil is generally well tolerated. When side effects do occur, they’re usually mild and temporary. Headaches, facial flushing and back pain are among the more common side effects and typically settle without treatment.
Tadalafil is the active ingredient in Cialis, a prescription oral tablet used to treat erectile dysfunction (ED). This means Cialis side effects are the same as tadalafil. The most common are headaches, flushing, indigestion, a blocked nose, and back or muscle aches. These usually ease within a few hours to a couple of days, and often become less noticeable over time.
Serious side effects are rare, but there are a few symptoms you should never ignore. This guide covers what to expect, how to reduce side effects and when to seek help.
What are the most common side effects of tadalafil?
Common side effects affect up to 1 in 10 men. They include:
Headaches - the most frequently reported side effect, usually a dull ache
Facial flushing - your face or neck may feel warm or look red
Indigestion - heartburn, bloating or discomfort in the upper stomach
Blocked or stuffy nose
Back pain and muscle aches - often felt in the lower back, buttocks or thighs
Pain in the arms or legs
These side effects can start within a few hours of taking tadalafil and usually improve within a few hours to a couple of days as your body adjusts.
Always read the patient information leaflet for a full list of potential side effects before starting any new medication.
What does tadalafil back pain feel like?
Back pain is more closely linked with tadalafil than with other erectile dysfunction (ED) tablets. The ache is usually dull, felt on both sides of the lower back, and can feel worse when lying down.
It can be unsettling, but it's usually mild. In trials, around 9% of men taking tadalafil 10mg reported back pain or muscle aches, compared with about 4% taking a placebo. Very few stopped treatment because of it and studies found no signs of muscle damage.
Some men describe aching in their arms and legs as joint pain, which is usually part of the same side effect. Joints that are swollen, red or hot aren't typical of tadalafil, though, and are worth getting checked.
How long do tadalafil side effects last?
While headaches, flushing and a stuffy nose usually appear within a few hours of a dose and fade within a few hours, back pain and muscle aches can last a little longer. They tend to appear 12 to 24 hours after a dose and normally clear up within 48 hours without treatment.
If you take tadalafil every day, most headaches happen in the first 10 to 30 days, then settle as your body adjusts.
Why does tadalafil cause side effects?
Side effects can affect different parts of the body because tadalafil doesn't only affect blood flow to the penis.
Tadalafil belongs to a group of medicines called PDE-5 inhibitors. It works by blocking an enzyme called cGMP-specific phosphodiesterase type-5 (PDE-5). This enzyme breaks down cGMP, a natural substance that makes smooth muscles relax. By blocking PDE-5, tadalafil increases the amount of cGMP in the smooth muscles, which relaxes and widens the blood vessels. In the penis, this means more blood can flow in when you’re aroused, making it easier to get and keep an erection.
The reason side effects happen is that PDE-5 isn’t only found in the penis, it’s found throughout the body. Levels are also high in the lungs as well as the penis. Moreover, PDE-6 is found in the retina. This means the same relaxing, widening effect happens in other places too, potentially leading to:
Headaches caused by wider blood vessels in the head
Flushing caused by blood flow to the skin
A blocked nose due to swollen blood vessels
Indigestion caused by relaxed muscles at the top of the stomach that can let acid rise
Blurred vision caused by PDE-6 in the retina
Most side effects are a normal by-product of how the medicine works, not a sign that something is wrong. Because tadalafil stays in the body for a long time (it can work for up to 36 hours), side effects can sometimes linger a little longer.
Are side effects more common at higher tadalafil doses?
Generally, yes. Headaches, indigestion, back pain and muscle aches become more likely as the dose goes up, although plenty of men take higher doses without any problems.
Tadalafil can be taken in two ways:
Dose | 2.5mg or 5mg | 10mg or 20mg |
How it's taken | Once a day, at around the same time | Before sex, no more than once a day |
What to expect | Side effects are most likely in the first few weeks and often fade as your body adjusts | Side effects tend to come and go with each dose and may be more noticeable at 20mg |
If tadalafil 20mg side effects are bothering you, your prescriber may suggest dropping to 10mg. Likewise, if tadalafil 5mg side effects don't settle, a 2.5mg daily dose is also an option.
What about less common side effects?
Less common side effects affect between 1 and 10 in every 1,000 men. They can include:
Dizziness or light-headedness - particularly when standing up quickly, after drinking alcohol or alongside blood pressure medication
A fast or pounding heartbeat - you may become more aware of your heartbeat than usual
Nausea or stomach discomfort - including feeling sick or experiencing acid reflux
Nosebleeds - usually mild and short-lived
Ringing in the ears (tinnitus) - a buzzing or ringing sound that may come and go
Blurred vision
Changes in blood pressure - tadalafil can lower blood pressure slightly, which may contribute to dizziness or light-headedness
These side effects are less common and are usually mild. If they persist, become severe or concern you, speak to a doctor or pharmacist.
Are there any serious side effects?
Serious side effects are uncommon or rare, affecting fewer than 1 in 100 men, and some affect fewer than 1 in 10,000. Whichever you notice, stop taking tadalafil and get medical help straight away:
An erection lasting more than 4 hours (priapism), especially if painful. It needs treating quickly to prevent lasting damage
Allergic reactions including rashes and swelling of the face, lips or throat
Chest pain, especially during or after sex. Call 999, don't use nitrates such as a GTN spray, and tell staff you've taken tadalafil
Sudden loss, dimming or distortion of vision
Sudden loss of hearing
Fainting or a seizure
How can you reduce or avoid tadalafil side effects?
If you're wondering how to avoid Cialis side effects, there’s no guaranteed way but a few simple steps can help:
Stick to your prescribed dose. Never take more than one dose in 24 hours.
Go easy on alcohol. Heavy drinking can lower your blood pressure, making dizziness more likely, and can make erections harder to get.
Stay hydrated. Drinking enough water may help with headaches.
Avoid grapefruit juice. It can raise the amount of tadalafil in your blood, making side effects more likely.
Treat symptoms simply. Paracetamol can help with headaches or back ache, and an antacid can ease indigestion. Check with a pharmacist first.
Give it time. Many side effects become milder after the first few doses or weeks.
Mention all your medicines. Some blood pressure treatments, antibiotics and antifungals can increase side effects.
If side effects are getting you down, don't stop treatment or change your dose on your own. Speak to your prescriber first. They may lower your dose, switch you between daily and on-demand tadalafil, or suggest a different treatment.
How do tadalafil side effects compare to sildenafil?
If you're weighing up Cialis side effects vs Viagra (sildenafil), the overall picture is relatively similar. Both can cause headaches, flushing, indigestion and a blocked nose, and neither causes more side effects overall.
The main difference is that tadalafil is more often linked with back pain and muscle aches. This is thought to be because it also has a small effect on a related enzyme, PDE11, found in muscle, although the exact cause isn't fully understood.
Sildenafil, on the other hand, is more often linked with temporary vision changes like a blue tint.
For a full comparison, including how quickly each works and how long they last, read our guide on sildenafil vs tadalafil.
What else should you know before starting tadalafil?
Tadalafil is suitable for most men, but not everyone. You shouldn't take it if you:
Take nitrates for angina (including GTN sprays) or use amyl nitrite (poppers)
Take riociguat, used for high blood pressure in the lungs
Have had a heart attack in the last 90 days or a stroke in the last 6 months
Have serious heart disease, low blood pressure, or high blood pressure that isn't controlled
Have ever lost vision due to NAION, sometimes called a "stroke of the eye"
Your prescriber will also need to know about kidney or liver problems, sickle cell anaemia, conditions affecting the shape of your penis, and any alpha-blockers you take. A proper consultation makes sure tadalafil is safe for you and that you start on the right dose.
Get expert ED advice from Quick Meds
Thinking about tadalafil, or have further questions about side effects? Start your online ED consultation and our prescribing team will review your medical history, medicines and preferences before recommending a treatment and dose that suits you.
Quick Meds is a GPhC-registered UK online pharmacy, and treatment is delivered discreetly to your door.
References
https://www.nhs.uk/medicines/tadalafil/
https://www.medicines.org.uk/emc/product/7432/pil
https://www.medicines.org.uk/emc/product/7432/smpc
https://www.accessdata.fda.gov/drugsatfda_docs/label/2007/021368s007lbl.pdf
https://www.nature.com/articles/3901374
https://www.nature.com/articles/6702908
