What is tadalafil – effects, Cialis, dosage and duration of action
5. June 2025
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🧬 What is Sildenafil? Effects, uses, dosage and risks
Sildenafil is a medication used to treat erectile dysfunction (ED) in men, a disorder in the ability to achieve or maintain an erection. It acts as an inhibitor of the phosphodiesterase type 5 (PDE5) enzyme and its main goal is to improve blood flow to the penis during sexual stimulation.
Sildenafil is one of the most well-known active ingredients in this field and is part of the famous drug Viagra, which was approved back in 1998 and became a breakthrough in the treatment of sexual disorders in men.
💊 Viagra – the original brand of Sildenafil
Viagra is the most well-known commercial name for sildenafil. It is manufactured by the pharmaceutical company Pfizer and is available in doses of 25 mg, 50 mg, and 100 mg.
- The usual dose is 50 mg before intercourse
- It is taken about 30 to 60 minutes before activity
- The effect lasts 4 to 5 hours
Viagra does not produce an erection automatically – sexual stimulation must be present.
In addition to Viagra, sildenafil is also available as a generic ( e.g. SildenaHEXAL, Sildenafil STADA, etc.), often at a lower price, but with the same effect.
🔬 How does sildenafil work?
During sexual arousal, the body releases nitric oxide, which activates enzymes leading to increased blood flow to the erectile bodies of the penis. However, the enzyme PDE5 quickly stops this process. Sildenafil temporarily blocks this enzyme, which allows blood flow to be maintained longer – and therefore a longer, better erection.
But sildenafil doesn’t work without sexual stimulation – it’s not an aphrodisiac.
📋 Dosage and method of use
- The recommended starting dose is 50 mg
- It is taken approximately 30 to 60 minutes before intercourse
- The maximum recommended dose is 100 mg per day
- It must not be taken more than once a day
The tablet is taken with water and can be taken with or without food, but heavy or fatty food may slow down the onset of action.
⚠️ Side effects
Common side effects of sildenafil include:
- Headache
- Redness of the face
- Runny nose or nasal congestion
- Digestive disorders
- Change in colour perception (blue vision)
Rare but serious side effects:
- Priapism – painful erection lasting more than 4 hours
- Sudden loss of hearing or vision
- Allergic reaction (swelling, rash, shortness of breath)
Sildenafil must not be combined with nitrate medications as it can cause a life-threatening drop in blood pressure.
❗ When not to take sildenafil?
Sildenafil is not suitable for everyone. Contraindications include:
- Heart disease (e.g. unstable angina)
- Low blood pressure
- Use of nitrates or nitric oxide donors
- Allergy to sildenafil or other ingredients
- Severe liver or kidney disease
It is always advisable to consult a doctor before taking it.
🤔 Sildenafil vs. other erection drugs
| Drug | Active ingredient | Onset of action | Duration of action | Advantage |
|---|---|---|---|---|
| Viagra | Sildenafil | 30–60 minutes | 4–5 hours | The most famous, widely available |
| Cialis | Tadalafil | 30 minutes | up to 36 hours | Long effectiveness, suitable even daily |
| Levitra | Vardenafil | 25–60 minutes | 4–5 hours | Good efficacy at lower doses |
| Spedra | Avanafil | 15–30 minutes | 4-6 hours | Rapid onset of action |
✅ Summary
Sildenafil is an effective and proven substance for the treatment of erectile dysfunction, mainly known under the brand name Viagra. It helps improve blood circulation to the penis and thus allows for a quality erection during sexual arousal. It has a rapid onset of action, a relatively short duration of action and is also available as a generic.
Although sildenafil is an effective solution for many men, its use should always be consulted with a doctor, especially due to potential interactions with other medications and medical conditions.
