Tadalafil Side Effects and Safety

Tadalafil shares a class with sildenafil, but its side-effect profile has its own emphasis, and its longer duration in the body has safety implications that are worth understanding properly. This article sets out both, plus the warning signs that mean seek help now.

The definitive source for any specific product remains the consumer medicine information supplied with a lawfully dispensed medicine, together with your prescriber or pharmacist.

The regulatory position first

Tadalafil is a Schedule 4 prescription-only medicine in Australia. That applies to every brand and every labelled strength. Supply lawfully requires a prescription from a registered Australian prescriber, and the TGA prohibits advertising prescription-only medicines directly to consumers. This article is educational, not promotional, and contains no dosing information.

Why the side effects look the way they do

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor. It slows an enzyme involved in relaxing smooth muscle in blood vessel walls. Because that enzyme is present in vessels throughout the body, the recognised effects are largely a consequence of wider vascular relaxation rather than something unexpected.

Commonly recognised effects

• Headache, the most frequently reported.
• Indigestion or reflux.
• Back pain and muscle aches. This is the effect most characteristically associated with tadalafil rather than sildenafil, and it is thought to relate to activity at a related enzyme in muscle tissue.
• Facial flushing.
• Nasal congestion.
• Dizziness, related to blood pressure changes.
• Limb pain.

Less commonly reported are palpitations, blurred vision, eye pain, ringing in the ears, rash, sweating and fatigue.

The duration point that matters

Tadalafil has a substantially longer half-life than sildenafil, meaning the body takes considerably longer to clear it. Marketing tends to present this purely as a convenience. The safety implications deserve equal attention.

• Side effects can persist longer. A headache or an episode of back pain may have a longer tail than with a shorter-acting ingredient.
• The nitrate contraindication remains relevant for longer. This is the most important practical consequence. If you develop chest pain and present to an emergency department, the treating team needs to know that you have taken a PDE5 inhibitor and when — because it directly determines which emergency medicines are safe to give.
• Interactions have a longer window. Anything that alters clearance affects a longer period.

A sensible habit: keep tadalafil on your medicines list, tell any new treating clinician about it, and do not treat it as an occasional item not worth mentioning.

Absolute contraindications

• Nitrates. Glyceryl trinitrate sprays, patches and tablets, isosorbide products, and the recreational inhalants known as poppers must never be combined with tadalafil. The combination can cause a severe, potentially fatal drop in blood pressure. There is no safe workaround.
• Riociguat, used for pulmonary hypertension, is likewise contraindicated.

Cautions requiring medical assessment

• Alpha-blockers, used for prostate symptoms and blood pressure, need careful management because of compounding blood-pressure effects.
• Significant cardiovascular disease. Recent heart attack, recent stroke, unstable angina, uncontrolled hypertension, severe heart failure and certain arrhythmias all require assessment first. Sexual activity is physical exertion, and whether that exertion is safe for you is a genuine clinical question.
• Severe liver or kidney impairment, which affect how the body handles and clears the medicine.
• Very low blood pressure.
• Inherited retinal conditions such as retinitis pigmentosa, and any previous episode of non-arteritic anterior ischaemic optic neuropathy.

Interactions to declare

Tadalafil is metabolised by liver enzymes shared with many other medicines. Certain antifungals, macrolide antibiotics and HIV protease inhibitors can raise circulating levels considerably; some medicines used for epilepsy and tuberculosis lower them; grapefruit juice is commonly mentioned.

Give your prescriber and pharmacist a complete list — prescription medicines, over-the-counter products, herbal supplements and anything purchased online. Pharmacists will do this review at no cost, and it is one of the highest-value five minutes in the whole process.

Seek urgent care for these

• Chest pain, pressure or tightness during or after sexual activity. Call emergency services and state that a PDE5 inhibitor has been taken and when.
• An erection lasting more than four hours (priapism). A medical emergency — permanent damage is possible if it is not treated promptly.
• Sudden loss or reduction of vision in one or both eyes.
• Sudden hearing loss or ringing in the ears.
• Fainting or collapse.
• Signs of an allergic reaction — facial swelling, difficulty breathing, widespread rash.

Products of unknown origin

If a product has not been through regulatory assessment, nobody can tell you its side-effect profile, because nobody can tell you what is in it. The TGA has issued repeated warnings that medicines of this type sold through unregulated overseas channels have been found to contain undeclared ingredients, incorrect amounts or contaminants.

Check whether a product appears on the Australian Register of Therapeutic Goods, look for a legible batch number, expiry date and manufacturer details, and treat any supplier willing to skip the prescription requirement as disqualifying. Store medicines in original packaging in a cool dry place away from sunlight, out of reach of children, and do not use past the expiry date.

If something happens that is not an emergency

Do not stop, change or supplement a prescribed medicine on your own initiative. Describe what you experienced, when it began and how long it lasted, to your prescriber or pharmacist — there are usually options. Adverse events can also be reported to the TGA, which is part of how safety monitoring works after a medicine is on the market.

the Australian Commission on Safety and Quality in Health Care and Healthdirect Australia both publish independent, plain-English material on this medicine class.

This article is general educational information about medicine side effects and safety, not medical advice. If you experience chest pain, an erection lasting more than four hours, or sudden vision or hearing loss, seek urgent medical care. Otherwise, speak with your doctor or pharmacist.