Cialis Side Effects (Tadalafil): Complete guide for UK patients

If you are prescribed tadalafil (Cialis) for erectile dysfunction or lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH), you have to consider the potential Cialis side effects. In general, the popular medication is well tolerated. It is also highly effective in improving erectile function. However, it can still cause unwanted side effects in some users.

Its active ingredient, tadalafil, puts Cialis in a group of medications called PDE5 inhibitors. The same goes for the generic versions of the drug, because generic Cialis contains the same active ingredient. Nowadays, it is also possible to buy Cialis online in the UK.

The majority of side effects associated with Cialis (tadalafil) are temporary and mild. However, some users may experience more serious problems, with certain complications requiring urgent medical attention. That’s why understanding the side effects of Cialis is a precondition for a safe and effective use of the medication.

How does Cialis work, and why do side effects occur?

Cialis (tadalafil) is a phosphodiesterase type 5 (PDE5) inhibitor. It blocks the PDE5 enzyme, preventing the breakdown of cGMP, a chemical responsible for widening blood vessels. This action helps relax smooth muscle tissue and allows the drug to increase blood flow to specific areas of the body (particularly the penis) [1]. Therefore, when an individual is sexually aroused, tadalafil improves blood flow and supports erectile function.

However, PDE5 inhibitors are not designed only to treat erectile dysfunction. They also affect blood vessels and smooth muscle tissues in several parts of the body, not only in the penis. As a result, side effects such as headaches, flushing, nasal congestion, or digestive discomfort may occur. This occurs because the same mechanisms that improve blood flow in the penis can also affect blood vessels and smooth tissues elsewhere in the body.

What are some common side effects of Cialis that most men experience?

Men taking Cialis usually report only mild side effects that often improve once the medication leaves the body or the body becomes accustomed to the treatment. Here’s an overview of such side effects:

Headache

One of the most common Cialis side effects is headache [2]. Studies show that this happens because the circulation in the head is affected by the widening of blood vessels. Staying hydrated, limiting alcohol intake and, where appropriate, using over-the-counter pain relief may help reduce symptoms. In most cases, headaches are temporary and resolve on their own as the effects of Cialis wear off.

Indigestion and heartburn

Indigestion, acid reflux, and heartburn are among the more frequently reported side effects of Cialis. This may happen because tadalafil relaxes smooth muscle tissue in the digestive tract [3]. Eating smaller meals, avoiding spicy foods, and not lying down immediately after taking medication may help minimise digestive discomfort.

Flushing and facial redness

When blood vessels near the skin surface dilate, facial flushing can occur. It usually manifests as temporary warmth and redness in the face, neck, or upper chest [4]. Facial flushing usually does not last long, and it is generally harmless.

Stuffy or runny nose

Some men, temporarily, notice a blocked or runny nose while taking Cialis. Nasal congestion develops when tadalafil affects the circulation within the nasal passages [5].

Back pain and muscle aches

Back pain and muscle aches are reported more commonly with tadalafil than with some other ED medications. Some men experience lower back pain and muscle aches, typically arising within the first day after taking Cialis and usually resolving within 48 hours. [2, 5] Additionally, some users experience muscle aches in the legs, back, and shoulders.

Researchers believe these symptoms may be related to tadalafil’s effect on enzymes and tissues outside the blood vessels involved in erectile function. The good thing is that these symptoms are usually mild and self-resolving.

What are the more serious Cialis side effects, and when to seek immediate help?

Serious side effects may occur, but they are not common. Here’s an overview of severe symptoms that require urgent medical assistance:

• Prolonged or painful erection lasting more than four hours

A prolonged erection that lasts over four hours is considered a medical emergency. Some men may also experience a painful erection, even without sexual stimulation [6]. Such an erection has the potential to permanently damage penile tissue and negatively affect future erectile function.

Men with sickle cell anaemia have a higher risk of developing this complication.

• Sudden loss of vision or hearing loss

Anyone experiencing sudden hearing, sudden vision loss, or significant new visual disturbances should stop taking Cialis and seek immediate medical attention.

Sudden vision loss in one eye may indicate non-arteritic anterior ischaemic optic neuropathy (NAION), a rare condition that has been associated with PDE5 inhibitors. Men who have previously experienced NAION in one eye should not take Cialis, as they may be at increased risk of NAION in the other eye [19].

Men with inherited eye disorders such as retinitis pigmentosa should discuss risks with their doctor before treatment.

• Severe allergic reactions and skin changes

An allergic reaction may present with rash, itching, swelling of the face, lips, or tongue, and breathing difficulties [7].

A serious allergic reaction can involve severe swelling of the face, lips, and tongue, together with difficulty breathing.

• Chest pain and a dangerous drop in blood pressure

Chest pain after taking Cialis is a medical emergency.

When tadalafil is combined with certain medications, it can contribute to low blood pressure [8]. This sudden decrease can, in turn, lead to dizziness, fainting, or collapse.

Sexual activity itself places additional strain on the cardiovascular system, which may increase risk in men with significant underlying heart disease [9].

Rare Cialis side effects in the treatment of erectile dysfunction

Several uncommon side effects have been reported during clinical trials and post-marketing surveillance [10]. These include:

• Jaw pain
• Abnormal vision
• Eye discomfort
• Sensitivity to light

Rare cardiovascular reactions have also been observed, including irregular heartbeat and episodes involving significant changes in blood pressure.

Daily Cialis side effects: 2.5 mg and 5 mg vs on-demand use

Unlike some other ED medications, tadalafil is fairly often prescribed for regular daily use to maintain a consistent level of the drug in the bloodstream [11]. Daily tadalafil tablets are usually available in 2.5 mg and 5 mg strengths.

The experience with daily use differs. Some patients report fewer noticeable side effects with daily therapy, possibly because drug levels remain relatively stable. Others may experience ongoing mild symptoms due to continuous exposure.

Therefore, the choice between daily Cialis and on-demand treatment depends on individual preferences, symptom severity, and the doctor’s recommendations.

Cialis side effects when used for an enlarged prostate

Tadalafil is also approved for treating symptoms associated with benign prostatic hyperplasia.

Daily use of the medication may improve urinary flow and reduce urinary frequency in men with benign prostatic hyperplasia [12]. However, the side effects may still occur.

That’s why it is important for men with an enlarged prostate to also consult their doctor whether daily tadalafil is suitable for their particular situation.

How to reduce Cialis side effects?

Most Cialis side effects can be minimised through proper dosing and healthy lifestyle choices:

How to choose the right dose for fewer side effects?

A higher dose of the medication does not always mean a better treatment result. The lowest effective dose is a much better option because it delivers the benefits and minimises the risk of side effects.

Doctors may also recommend lower doses for older adults, patients with kidney disease, or those taking interacting medications. Taking more tadalafil than prescribed increases the risk of unwanted reactions and is unlikely to provide additional benefit that outweighs those risks.

Why are timing, food, and lifestyle adjustments important?

Cialis can be taken with or without food. Unlike sildenafil, tadalafil's absorption is not meaningfully delayed by a heavy or high-fat meal, providing greater flexibility around mealtimes. However, healthy habits can improve overall tolerability and minimise the risk of side effects. Such habits include:

• Limiting alcohol consumption
• Staying hydrated
• Exercising regularly
• Maintaining a healthy weight

Additionally, a healthy lifestyle also supports better erectile function and helps treat ED more effectively.

Can you drink alcohol when taking Cialis for erectile function?

Alcohol and tadalafil both influence blood pressure, increasing the risk of dizziness, headaches, and fainting [13]. Heavy drinking when taking Cialis may also lead to a severe drop in blood pressure. Flushing and headaches are also worsened by alcohol.

Furthermore, if you have had too much alcohol while taking Cialis Daily, you may accidentally forget to take your daily pill. Over time, it may become harder to tell whether the reduced effectiveness is due to the missed dose or the effects of the alcohol itself.

Grapefruit Juice and Cialis: An often overlooked interaction

Grapefruit juice can affect the enzymes that metabolise tadalafil [17]. This may result in too much tadalafil in the body and increase the risk of unwanted reactions.

Which medications must you not take with Cialis?

As with most ED medications, interactions with other drugs are among the most important safety considerations when taking Cialis. Here are more details:

• Nitrates and chest pain medicines

You should never combine nitrate medications used to treat angina and other forms of chest pain with tadalafil.

The combination can cause a dangerous and sudden decrease in blood pressure, potentially leading to loss of consciousness or life-threatening complications [14].

• Alpha-Blockers and blood pressure medications

Alpha blockers used for prostate conditions and certain forms of high blood pressure treatment can interact with tadalafil, increasing the risk of dizziness and fainting.

• Antifungals, antibiotics and HIV medicines

Certain prescription drugs may also increase tadalafil levels in the bloodstream [15]. Examples include some oral antifungal medications, antibiotics, and HIV medicines that affect liver enzymes responsible for drug metabolism (consequently leading to too much tadalafil in the bloodstream).

• Recreational drugs and poppers

Many recreational drugs can interact dangerously with tadalafil. Nitrate-containing poppers are particularly hazardous because they can trigger severe drops in blood pressure [16]. Some recreational drugs can increase heart rate and cardiovascular stress, which may increase health risk in susceptible individuals.

Who should not take Cialis?

Tadalafil is generally very safe, but it is not appropriate for everyone. Here’s an overview:

• Heart conditions and low blood pressure

Patients with unstable cardiovascular disease, recent heart attack, unstable angina, or certain forms of severe heart failure may not be suitable candidates for tadalafil-based ED treatment [18].

Men with low blood pressure, severe cardiovascular disease, uncontrolled high blood pressure, or complex pulmonary vascular conditions should undergo a specialist evaluation before taking Cialis.

Individuals with pulmonary arterial hypertension already using other PDE5 inhibitors should not take tadalafil, as concurrent use of two PDE5 inhibitors is contraindicated. [16, 19]

• Impaired kidney and liver function

Kidney disease can slow the elimination of tadalafil from the body. Therefore, men with kidney impairment or severe liver disease often require lower doses to prevent excessive drug accumulation and reduce the risk of side effects [19].

• Enlarged prostate and other urological conditions

Men with Peyronie's disease, a significant penile curvature, a history of prolonged erections, or other significant urological conditions should discuss treatment carefully with a medical expert [20].

Are side effects more common in older men?

Older adults may be more sensitive to certain Cialis side effects [21]. These particularly include dizziness and changes in blood pressure. Additionally, age-related changes in kidney function can affect how the body processes all medications, including tadalafil. So, caution and medical supervision are advised.  

Cialis vs Viagra: How do the side effects compare?

Both Cialis and Viagra are well-known brand names (generic versions exist). They belong to the PDE5 inhibitor family and are commonly prescribed for erectile dysfunction [22]. Like Cialis, you can also buy Viagra online. Both medicines are available through regulated UK healthcare providers following an appropriate medical assessment.

However, these medications contain a different active ingredient. Cialis contains tadalafil, while Viagra contains sildenafil citrate.

When comparing Cialis side effects vs Viagra (Sildenafil vs Tadalafil), we can say that both medications commonly cause:

• Headaches
• Flushing
• Nasal congestion

However, tadalafil is more frequently associated with back pain and muscle aches, while sildenafil citrate may be more likely to cause visual disturbances.

Both medications effectively improve ED. However, some men may respond better to one medication than the other.

Cialis Side Effects FAQs

Here are the answers to some frequently asked questions about Cialis side effects:

How long do Cialis side effects last?

Most side effects resolve within a few hours to two days. Because tadalafil remains active longer than many ED drugs, some symptoms may persist longer compared with alternatives.

Can Cialis cause joint pain or muscle aches?

Yes. Mild and temporary back pain and muscle aches are scientifically recognised side effects of Cialis.

What are the long-term risks of taking Cialis?

Current evidence suggests tadalafil remains well tolerated during long-term use. No physical dependence or progressive loss of effectiveness has been demonstrated in most patients, although ongoing medical review is recommended.

What should I do if Cialis side effects don't go away?

Persistent side effects require professional medical attention. Dose adjustments or alternative ED drugs may be considered.

Is it normal to still have side effects after taking Cialis several times?

Yes. While some men adapt to treatment, others continue experiencing mild Cialis side effects even after repeated use.

Can Cialis side effects start the next day?

Yes. Because tadalafil remains active for up to 36 hours, side effects such as headache, muscle aches, or back pain may occur several hours after taking a dose.

Can Cialis be addictive?

No. Tadalafil is not physically addictive and does not cause dependence. However, some men may become psychologically reliant on ED medication for confidence.