“I’ve been prescribed Viagra, but I’m not 100% sure when to take it.”
“My GP mentioned testosterone gel, but how do you use that?”
“Will I need to be on testosterone replacement forever?”
If you’ve been prescribed medication for erectile dysfunction or low testosterone, knowing how to use it properly makes a real difference to how well it works and how confident you feel.
In this guide, we’ll cover the medications most commonly prescribed at Summerhill Health for men’s sexual and hormonal health, including Sildenafil, Tadalafil, Testogel, Testavan, Testosterone cypionate and Kyzatrex, with practical advice on dosing, timing, and what to expect.
At Summerhill Health, Dr Natalie Summerhill works within guidance from NICE, the RCGP, and the British Association of Urological Surgeons to support men with erectile dysfunction, low testosterone, and related concerns. Every treatment plan is personalised to your symptoms, your medical history, your lifestyle, and your goals.
Please note: This guide provides general information only. Always follow the specific instructions your GP has given you, and contact us if you’re unsure about anything.
In this guide
- Why Erectile Dysfunction Happens and How Medication Helps
- How to Take Sildenafil
- How to Take Tadalafil
- Comparing Sildenafil and Tadalafil
- Why Replacement May Be Recommended for Low Testosterone
- How to Use Testogel
- How to Use Testavan
- How to Use Testosterone Cypionate
- How to Use Kyzatrex
- Comparing Testosterone Options
- What to Expect When Starting Treatment
- How to Store Your Medications
- Frequently Asked Questions
- When to Contact the Clinic
- Ready to Take the Next Step?
Why Erectile Dysfunction Happens and How Medication Helps
Erectile dysfunction (ED) is the persistent difficulty getting or maintaining an erection firm enough for satisfactory sexual activity. It’s extremely common, affecting around half of men between the ages of 40 and 70 to some degree.
ED can be caused by a combination of physical and psychological factors. Common contributors include cardiovascular disease, diabetes, high blood pressure, stress, anxiety, and certain medications. It can also be an early warning sign of underlying health conditions, which is why we always take your symptoms seriously and investigate the cause alongside treating the symptoms.
PDE5 inhibitors (such as sildenafil and tadalafil) work by increasing blood flow to the penis when you’re sexually aroused. They don’t create arousal on their own. You still need physical stimulation for them to work.
How to Take Sildenafil
Sildenafil (the active ingredient in Viagra) is a short-acting PDE5 inhibitor taken on an as-needed basis.
- The usual starting dose is 50mg, taken approximately 1 hour before sexual activity. It can work in as little as 30 minutes for some men.
- Your dose may be adjusted to 25mg or 100mg depending on how well it works and whether you experience side effects.
- Do not take more than one dose in 24 hours.
- Sildenafil works best on an empty stomach or after a light meal. A heavy or fatty meal can delay how quickly it takes effect.
- The effects typically last 4 to 6 hours, though this varies between individuals.
A few practical tips:
- Give it a fair trial. Sildenafil may not work perfectly the first time. Most specialists recommend trying it on at least 6 to 8 separate occasions before concluding it isn’t effective.
- Alcohol can reduce effectiveness. A small amount is unlikely to cause problems, but heavy drinking makes ED worse and can reduce how well the medication works.
- Do not take sildenafil with nitrates (such as GTN spray or isosorbide mononitrate). The combination can cause a dangerous drop in blood pressure. If you use nitrates for angina, let us know before starting treatment.
How to Take Tadalafil
Tadalafil (the active ingredient in Cialis) is a longer-acting PDE5 inhibitor. It comes in two dosing options, which is one of the reasons many men prefer it.
As-needed dosing
- The usual starting dose is 10mg, taken at least 30 minutes before sexual activity.
- Your dose may be adjusted to 20mg depending on how well it works.
- Do not take more than one dose in 24 hours.
- The effects can last up to 36 hours, which gives more flexibility and spontaneity compared to sildenafil. This doesn’t mean you’ll have an erection for 36 hours. It means the medication remains active in your system, so you can respond to arousal naturally during that window.
Daily dosing
- If you anticipate sexual activity at least twice a week, a daily low dose may suit you better.
- The usual dose is 5mg once daily, taken at the same time each day (with or without food).
- Daily tadalafil provides a continuous low level of the drug in your system, so you don’t need to plan around taking a tablet before sex.
- Tadalafil 5mg daily is also licensed to treat benign prostatic hyperplasia (enlarged prostate), so if you have both conditions, it can address them together.
The same safety rules apply as for sildenafil: do not take tadalafil with nitrates, and let us know about all your current medications before starting.
How to Take Sildenafil
Sildenafil (the active ingredient in Viagra) is a short-acting PDE5 inhibitor taken on an as-needed basis.
- The usual starting dose is 50mg, taken approximately 1 hour before sexual activity. It can work in as little as 30 minutes for some men.
- Your dose may be adjusted to 25mg or 100mg depending on how well it works and whether you experience side effects.
- Do not take more than one dose in 24 hours.
- Sildenafil works best on an empty stomach or after a light meal. A heavy or fatty meal can delay how quickly it takes effect.
- The effects typically last 4 to 6 hours, though this varies between individuals.
A few practical tips:
- Give it a fair trial. Sildenafil may not work perfectly the first time. Most specialists recommend trying it on at least 6 to 8 separate occasions before concluding it isn’t effective.
- Alcohol can reduce effectiveness. A small amount is unlikely to cause problems, but heavy drinking makes ED worse and can reduce how well the medication works.
- Do not take sildenafil with nitrates (such as GTN spray or isosorbide mononitrate). The combination can cause a dangerous drop in blood pressure. If you use nitrates for angina, let us know before starting treatment.
How to Take Tadalafil
Tadalafil (the active ingredient in Cialis) is a longer-acting PDE5 inhibitor. It comes in two dosing options, which is one of the reasons many men prefer it.
As-needed dosing
- The usual starting dose is 10mg, taken at least 30 minutes before sexual activity.
- Your dose may be adjusted to 20mg depending on how well it works.
- Do not take more than one dose in 24 hours.
- The effects can last up to 36 hours, which gives more flexibility and spontaneity compared to sildenafil. This doesn’t mean you’ll have an erection for 36 hours. It means the medication remains active in your system, so you can respond to arousal naturally during that window.
Daily dosing
- If you anticipate sexual activity at least twice a week, a daily low dose may suit you better.
- The usual dose is 5mg once daily, taken at the same time each day (with or without food).
- Daily tadalafil provides a continuous low level of the drug in your system, so you don’t need to plan around taking a tablet before sex.
- Tadalafil 5mg daily is also licensed to treat benign prostatic hyperplasia (enlarged prostate), so if you have both conditions, it can address them together.
The same safety rules apply as for sildenafil: do not take tadalafil with nitrates, and let us know about all your current medications before starting.
Comparing Sildenafil and Tadalafil
| Sildenafil | Tadalafil (as needed) | Tadalafil (daily) | |
|---|---|---|---|
| Typical dose | 50mg (range 25 to 100mg) | 10mg (up to 20mg) | 5mg once daily |
| When to take | 1 hour before activity | At least 30 minutes before activity | Same time each day |
| Duration of effect | 4 to 6 hours | Up to 36 hours | Continuous |
| Affected by food? | Yes (fatty meals delay onset) | No | No |
| Best suited to | Planned, less frequent activity | Flexibility and spontaneity | Regular activity; also treats enlarged prostate |
There’s no single “best” option. The right choice depends on how often you’re sexually active, whether you prefer to plan ahead or be spontaneous, and how your body responds. We can help you find the right fit.
Why Replacement May Be Recommended for Low Testosterone
Testosterone levels naturally decline from your mid-to-late 30s onwards, typically by about 1% per year. For most men, this gradual change doesn’t cause noticeable symptoms. But some men develop testosterone deficiency (sometimes called androgen deficiency in ageing males, or ADAM), where levels fall low enough to affect quality of life.
Common symptoms of low testosterone include:
- Persistent fatigue and low energy
- Reduced libido and erectile difficulties
- Loss of muscle mass and increased body fat
- Low mood, irritability or difficulty concentrating
- Reduced motivation
We only prescribe testosterone replacement therapy (TRT) after confirming low levels through blood tests taken in the morning on at least two separate occasions, alongside a thorough clinical assessment. TRT is not appropriate for men with normal testosterone levels.
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How to Use Testogel (Testosterone Gel)
Testogel is a transdermal testosterone gel applied to the skin once daily. It delivers a steady supply of testosterone through the skin into the bloodstream.
- The usual starting dose is one sachet or pump equivalent daily (either 50mg/5g or 40.5mg/2.5g, depending on the formulation prescribed).
- Apply the gel in the morning, to clean, dry skin on your shoulders and upper arms.
- Spread the gel as a thin layer. You don’t need to rub it in vigorously.
- Allow it to dry for 3 to 5 minutes before getting dressed.
- Wash your hands thoroughly with soap and water after application.
- Wait at least 2 to 6 hours before showering or bathing (check the specific guidance for your formulation, as the required time varies between 1% and 16.2% gels).
- Do not apply to the genital area, as the high alcohol content in the gel can cause irritation.
Avoiding transfer to others
Please note: Testosterone gel can transfer to other people through skin-to-skin contact, which can cause unwanted effects, particularly in women and children.
- Once the gel has dried, cover the application area with clothing (such as a T-shirt).
- If skin-to-skin contact with another person is likely before you’ve showered, wash the application area first.
- If another person accidentally comes into contact with the gel, they should wash the affected area with soap and water promptly.
How to Use Testavan (Testosterone Gel)
Testavan is another transdermal testosterone gel, applied once daily using a metered-dose pump. Like Testogel, it delivers a steady supply of testosterone through the skin into the bloodstream.
- The usual dose is 1 to 3 pumps daily, adjusted to your blood levels and clinical response.
- Apply it in the morning to clean, dry skin on the upper arms and shoulders, using the applicator provided so you avoid getting gel on your hands.
- Allow it to dry before getting dressed, and cover the area with clothing once dry.
- Some men experience irritation at the application site, such as redness or itching. Rotating where you apply it can help, so let us know if it persists.
- The same transfer precautions apply as for any testosterone gel: cover the area once dry, and wash the area before close skin-to-skin contact with others.
How to Use Testosterone Cypionate (Injectable Testosterone)
Testosterone cypionate is an injectable form of testosterone, given as an intramuscular injection (usually into the gluteal muscle).
- The typical dose is 50 to 200mg, administered every 2 to 4 weeks, depending on your blood levels and clinical response.
- Many modern TRT protocols use more frequent, lower doses (for example, every 1 to 2 weeks) to maintain more stable blood levels and avoid the peaks and troughs that can occur with less frequent injections.
- Some men are trained to self-inject at home after an initial demonstration at the clinic. Others prefer to attend for their injections.
- The injection site should be rotated to reduce discomfort and the risk of local tissue irritation.
Your dose and frequency will be adjusted based on regular blood tests. We monitor testosterone levels, haematocrit (red blood cell count), PSA (prostate-specific antigen), and liver function to ensure treatment is safe and effective.
How to Use Kyzatrex (Oral Testosterone)
Kyzatrex is an oral testosterone capsule (testosterone undecanoate), offering a tablet-based alternative for men who would rather avoid gels or injections. It is currently unlicensed in the UK, which means we prescribe it on a named-patient basis where it’s clinically appropriate. We’ll explain exactly what that means for you before you start.
- We can only source 200mg capsules at the clinic. Ideally the dose is titrated in steps of 50mg, so we’ll talk through how best to manage this with the strength available.
- The maximum dose is 200mg four times daily.
- Take it with a meal containing some fat, as dietary fat significantly aids absorption.
- It is a large capsule, which some men find difficult to swallow. Take it with a full glass of water, and let us know if swallowing is a problem so we can look at alternatives.
- As with all TRT, your dose will be guided by regular blood tests.
Comparing Testosterone Options
| Testogel | Testavan | Testosterone cypionate | Kyzatrex | |
|---|---|---|---|---|
| Route | Gel applied to skin daily | Gel applied to skin daily (pump) | Intramuscular injection every 1 to 4 weeks | Oral capsule |
| Testosterone delivery | Steady daily absorption | Steady daily absorption | Peak after injection, then gradual decline | Absorbed via the gut; aided by dietary fat |
| Convenience | Daily application; no needles | Daily application; no needles | Less frequent; can self-inject at home | Daily capsules; no needles or skin transfer |
| Considerations | Risk of transfer to others; must cover application site | Possible application-site irritation; risk of transfer to others | Requires injection technique; possible injection site discomfort | Unlicensed in the UK; large capsule can be hard to swallow; take with fatty food |
| Best suited to | Men who prefer a daily routine and want steady levels | Men who prefer a daily routine and want steady levels | Men who prefer less frequent dosing or find gel inconvenient | Men who prefer an oral option and want to avoid gels or injections |
What to Expect When Starting Treatment
Erectile dysfunction medications
Most men notice an improvement within the first few uses, though it can take several attempts to find the right dose and timing. Common early side effects include headache, facial flushing, nasal congestion, and indigestion. These usually settle as your body adjusts and are generally mild.
If you experience visual disturbances, dizziness, or a prolonged erection lasting more than 4 hours (priapism), seek urgent medical advice.
Testosterone replacement
Improvements in energy, mood, and libido often begin within the first 4 to 6 weeks, though the full effects of TRT can take 3 to 6 months. Changes in body composition (muscle gain, fat reduction) tend to develop more gradually.
Common early effects include mild acne, oily skin, and changes in mood or energy as your body adjusts. These usually settle within the first few months.
Regular blood tests are essential, typically at 3 months after starting treatment and then annually. We monitor your testosterone levels alongside haematocrit, PSA, and liver function to ensure treatment remains safe.
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How to Store Your Medications
- Sildenafil and tadalafil tablets: Store at room temperature, away from moisture and direct sunlight. Keep in the original packaging.
- Testogel sachets: Store at room temperature, below 25°C. Do not refrigerate. Keep sachets sealed until use.
- Testosterone cypionate: Store at room temperature. Do not freeze. Keep vials in the original carton to protect from light.
Keep all medications out of reach of children and do not use beyond the expiry date.
Frequently Asked Questions
Can I take sildenafil and tadalafil together?
No. These are both PDE5 inhibitors and should never be combined. If one isn’t working well for you, we can discuss switching to the other or adjusting your dose.
Will ED medication work if I don’t have erectile dysfunction?
PDE5 inhibitors are designed to treat ED. They are not performance enhancers and are unlikely to make a noticeable difference if your erections are already normal. Taking them without a clinical need also exposes you to unnecessary side effects.
Can I buy sildenafil over the counter?
Sildenafil 50mg is available from pharmacies without a prescription (sold as Viagra Connect). However, we’d always recommend a proper assessment first, because ED can be a sign of underlying health issues that are worth investigating.
How long will I need to take testosterone?
TRT is usually a long-term commitment. If you stop, your testosterone levels will return to where they were before treatment, and symptoms are likely to come back. We’ll review your treatment regularly to make sure it’s still right for you.
Can testosterone replacement affect my fertility?
Yes. Testosterone replacement can significantly reduce sperm production and is not suitable as a treatment if you’re trying to conceive. If fertility is a concern, we’ll discuss alternative approaches before starting TRT.
Is it safe to use Testogel if I have a partner?
Yes, as long as you follow the transfer precautions. Cover the application area with clothing once it’s dry, wash your hands after applying, and wash the area before close skin-to-skin contact. These simple steps are effective at preventing transfer.
When to Contact the Clinic
Get in touch if:
- Your ED medication isn’t working after 6 to 8 attempts at the correct dose.
- You’re experiencing troublesome side effects that aren’t settling.
- You have questions about switching between ED medications.
- Your testosterone symptoms aren’t improving after 3 months of treatment.
- You notice any breast tenderness, significant mood changes or changes in urination while on TRT.
- You have any questions or concerns.
Seek urgent medical advice if you experience chest pain, a prolonged erection lasting more than 4 hours, sudden visual or hearing changes, or severe dizziness. These are rare but require immediate assessment.
Ready to Take the Next Step?
If you’re experiencing symptoms of erectile dysfunction or low testosterone, or if you have questions about your current treatment, our team at Summerhill Health is here to help. Our consultations are completely confidential, and our same-day and evening appointments mean you don’t have to wait.
Contact us on 0161 552 2382 or book an appointment online.
