Category: Active ingredients

  • Sildenafil, tadalafil, vardenafil and avanafil: key differences

    Sildenafil, tadalafil, vardenafil and avanafil are phosphodiesterase type 5 inhibitors, usually shortened to PDE5 inhibitors. They are used for erectile dysfunction but differ in onset, duration and the way food or other medicines may influence them.

    What they share: they support the erectile response by improving blood flow, but do not automatically create desire or an erection. Sexual stimulation is still required.

    A simple comparison

    Active ingredient Distinctive feature Effect of food
    Sildenafil Well-known option generally taken in advance A large meal may delay onset
    Tadalafil Longer window of action and prescribed daily options Usually less affected by food
    Vardenafil Profile similar to sildenafil, with different formulations available High-fat meals may delay onset
    Avanafil Designed for a relatively rapid onset Food may delay the effect

    Timings in patient leaflets are guides rather than guarantees. Individual response, food, alcohol, health conditions and other medicines can change the result. “Faster” or “longer” does not automatically mean “better”.

    How an appropriate option is chosen

    The decision may consider frequency of sexual activity, desired spontaneity, previous side effects, other medicines and cardiovascular, kidney or liver conditions. A previous response can help guide a clinician, but does not make self-directed switching safe.

    Shared precautions

    • Do not combine two erectile dysfunction medicines.
    • Do not use them with nitrates for angina or with riociguat.
    • Mention treatment for blood pressure, prostate symptoms, HIV or fungal infections.
    • Seek medical advice if sexual activity has been discouraged for heart-related reasons.
    • Do not change the dose or frequency without professional guidance.

    Possible side effects

    Headache, flushing, indigestion and nasal congestion are common across the class. Tadalafil may also cause back or muscle pain. Sudden vision or hearing symptoms and a prolonged painful erection require medical attention.

    Related guides: sildenafil explained and tadalafil duration and precautions.

    Sources

  • Sildenafil: how it works and what to know before use

    Sildenafil is the active ingredient made well known by Viagra and is also available in authorised generic medicines. It is used for erectile dysfunction in adult men when obtaining or maintaining an erection is difficult.

    How sildenafil works

    During sexual stimulation, the body releases signals that relax blood vessels in the penis. Sildenafil slows the breakdown of one of these signals, cGMP, which supports increased blood flow. It is not an aphrodisiac and does not work without arousal.

    Food, alcohol and expectations

    A high-fat meal may delay the start of the effect. Large amounts of alcohol can make an erection more difficult and increase some side effects. The response should not be judged like an instant switch: stimulation, context and correct use all matter.

    Common side effects

    • headache;
    • facial flushing;
    • indigestion;
    • nasal congestion;
    • dizziness or temporary changes in vision.

    Not everyone experiences these effects. Contact a doctor or pharmacist if a symptom is severe, unusual or persistent.

    When sildenafil may not be suitable

    Sildenafil must not be combined with nitrates used for angina and requires caution with some cardiovascular treatments. Tell a clinician about all medicines and relevant health conditions, particularly heart disease, very low blood pressure, liver or kidney disease and previous serious vision problems.

    Warning signs

    Chest pain, sudden loss of vision or hearing and a painful erection lasting longer than four hours require urgent medical attention. If chest pain occurs after sildenafil, do not use nitrates to treat it; tell the medical team what you have taken.

    Related guides: sildenafil, tadalafil, vardenafil and avanafil compared and generic and brand-name medicines.

    Sources

  • Tadalafil: duration, characteristics and precautions

    Tadalafil is a PDE5 inhibitor used for erectile dysfunction. Cialis is the best-known brand, and authorised generic versions are also available. Its best-known characteristic is a longer window of action than several other medicines in the same class.

    A longer window of action does not mean a continuous erection. Tadalafil supports the response only when sexual stimulation is present.

    What does “up to 36 hours” mean?

    After the prescribed dose, the ability to respond to stimulation may remain supported for an extended period. It does not guarantee the same intensity throughout that time, and actual duration varies between individuals.

    As-needed and daily schedules

    Tadalafil may be prescribed as needed or, at specific lower doses, once daily. These are different strategies. A daily schedule should not be created by splitting or repeatedly taking tablets intended for as-needed use. The choice depends on frequency of sexual activity, tolerability and health conditions.

    Common side effects

    Headache, indigestion, flushing, nasal congestion, back pain and muscle aches are among the more commonly reported effects. A clinician can help determine whether a symptom is expected or requires a change.

    Interactions and contraindications

    • Do not take tadalafil with nitrates or riociguat.
    • Mention medicines used for high blood pressure or prostate symptoms because the combination may lower blood pressure.
    • Seek advice if you have heart, kidney or liver disease.
    • Do not combine tadalafil with another erectile dysfunction treatment.

    When urgent help is needed

    Seek urgent medical help for chest pain, sudden loss of vision or hearing, a serious allergic reaction or a painful erection lasting longer than four hours.

    Related guides: compare common PDE5 inhibitors and what to check when treatment does not work.

    Sources

  • Generic and brand-name medicines: what really changes?

    People often use the word “generic”, while regulators usually refer to an equivalent or generic medicine. An authorised generic must meet defined quality standards and demonstrate that it delivers the active ingredient in a way that is comparable with the reference medicine.

    What must be the same?

    An authorised generic contains the same active ingredient and is used at the same dose for the same condition as its reference medicine. It must meet the same standards for quality, manufacturing and safety. Bioequivalence studies are used to confirm that exposure to the active ingredient falls within an accepted range.

    What may be different?

    • the product name and manufacturer;
    • colour, shape and packaging;
    • some inactive ingredients;
    • price.

    Inactive ingredients do not change the active substance, but they can matter for people with an allergy or intolerance. Always check the patient leaflet and ask a pharmacist if you are unsure.

    Why are generic medicines often less expensive?

    After patent protection for the reference medicine expires, other manufacturers can apply for authorisation without repeating the entire original development programme. A lower price therefore does not, by itself, indicate lower quality.

    Authorised generic does not mean unverified product

    The term generic applies to medicines assessed by the relevant authorities. A product from an unclear source, with incomplete labelling or unverifiable packaging, is not automatically a legitimate generic simply because it claims to contain the same ingredient.

    How to choose

    Availability, price, inactive ingredients and personal preference may all influence the choice. If you use prescription medicine or have other health conditions, discuss any substitution with a doctor or pharmacist.

    Related guides: how sildenafil works and tadalafil duration and precautions.

    Sources