Sildenafil Tablets
Sildenafil is a prescription treatment for erectile dysfunction in adult men. Available in three strengths (25mg, 50mg, 100mg), it is taken as needed about 1 hour before sexual activity. This medication is available through Chemist Doctor's regulated online service following a consultation with UK-licensed clinicians.
You must complete a short online consultation so that our prescriber can ensure that the treatment is suitable for you.
Assessment
Answer some questions about your health concerns & symptoms
Treatment
Connect with a clinician 100% online, no appointment needed
Delivery
Get your medication delivered directly, if prescribed
What is Sildenafil?
Sildenafil (commonly known as generic Viagra) is a PDE5 inhibitor medication used to treat erectile dysfunction. It works by enhancing blood flow to penile tissues during sexual stimulation through targeted vasodilation.
Key Mechanism of Action
When sexually aroused, the body releases cyclic guanosine monophosphate (cGMP) which relaxes penile blood vessels. Sildenafil's 36-hour effectiveness comes from inhibiting phosphodiesterase-5 (PDE5), the enzyme that breaks down cGMP. This biological process maintains increased blood flow to the corpus cavernosum, facilitating sustainable erections.
| Brand Name | Generic Equivalent | Onset Time |
|---|---|---|
| Viagra | Sildenafil | 30-60 minutes |
Understanding Erectile Dysfunction
Erectile dysfunction (ED) affects 1 in 5 UK men aged 40+ according to NHS data. It manifests as either:
- Inconsistent ability to achieve erection
- Difficulty maintaining erection during intercourse
- Reduced sexual stamina
Common Causes
Physical Factors
- Cardiovascular conditions
- Diabetes-related neuropathy
- Hormonal imbalances
Psychological Factors
- Performance anxiety
- Chronic stress
- Relationship issues
Sildenafil Treatment for Erectile Dysfunction
Clinical studies show 76% efficacy rates for Sildenafil in treating vasculogenic ED (NICE TA65). Ideal candidates include:
- Men with occasional ED episodes
- Patients preferring on-demand treatment
- Those without contraindications for PDE5 inhibitors
Who Should Not Take Sildenafil?
While erectile dysfunction treatment with Sildenafil benefits many patients, certain medical conditions and medication combinations pose absolute contraindications:
Absolute Contraindications
- Current nitrate therapy (e.g., glyceryl trinitrate for angina)
- Recent myocardial infarction (within last 6 months)
- Hypotension (BP <90/50 mmHg)
- History of NAION (non-arteritic anterior ischaemic optic neuropathy)
Medication Interactions
- Nitric oxide donors (e.g., amyl nitrate "poppers")
- Riociguat (Adempas®) for pulmonary hypertension
- HIV protease inhibitors
Pre-existing Conditions
- Severe hepatic impairment (Child-Pugh C)
- Penile deformities (Peyronie's disease)
- Haematological malignancies
According to NICE guidelines, 12% of ED patients require alternative therapies due to contraindications.
Sildenafil Treatment Safety Profile
Clinical trials report NHS-verified side effect rates:
| Frequency | Common Effects | Rare Effects |
|---|---|---|
| >10% | Headache, Flushing | Hypotension |
| 1-10% | Dyspepsia, Nasal congestion | Priapism |
Allergic Reaction Protocol
Immediately discontinue use if experiencing:
- Angioedema (facial swelling)
- Generalised urticaria
- Respiratory distress
Seek emergency care at your nearest NHS A&E department if systemic reactions occur.
Essential Sildenafil Safety Guidelines
- Maximum dosage: 100mg/24hrs
- Storage: Below 25°C in original packaging
- Disposal: Return unused tablets to any UK pharmacy
Priapism Management
Contact 111 immediately for erections lasting:
- >4 hours without stimulation
- >6 hours with partial rigidity
Where Can I Buy Sildenafil Online in the UK
Secure Sildenafil Prescription & Next-Day Delivery Service
Order Sildenafil with confidence through our UK-registered medical prescribers, who review all requests within 4 working hours. We guarantee same-day prescription approval for eligible patients and dispatch orders placed before 3pm for next-day tracked delivery.
Our Sildenafil service combines competitive pricing with strict adherence to MHRA safety standards, ensuring your medication is dispensed through GPhC-registered pharmacies. Every purchase includes discreet packaging and a GDPR-compliant consultation process.
Our Sildenafil clinical team ensures:
- Full medical history review
- Drug interaction checks
- Ongoing safety monitoring
Getting your medication is quick and easy with our simple 4-step process:
Start Consultation
Complete our brief health questionnaire about your medical history and current health.
Medical Review
UK-registered clinicians review your consultation for safe prescribing.
Pharmacy Processing
If approved, our partner pharmacy prepares your medication.
Fast Dispatch
Your order is dispatched via your chosen delivery method.
What does the online consultation involve?
You'll answer questions about your medical history and current health to ensure safe prescribing. Honest responses are vital for your safety.
How do I reorder medication?
Use the login details emailed after your first order to access your account and reorder.
How does the secure chat portal work?
Clinicians may contact you via your account's chat portal to discuss your treatment. Respond securely within your account.
At Chemist Doctor, we respect your privacy and ensure complete discretion at every step.
Discreet Packaging
All orders are shipped in discreet, tamper-evident packaging sealed inside anonymous mailing bags.
Secure Data
Your personal and medical information is kept strictly confidential with SSL encryption.
Private Consultations
All consultations are conducted privately by UK-registered clinicians.
Anonymous Billing
Credit card statements show a neutral descriptor with no reference to medications.
Will my GP be informed about my order?
Only with your consent. We recommend updating your GP directly for seamless care.
We offer two reliable delivery options to suit your needs:
| Service Type | Delivery Speed | Order Cut-off | Carrier |
|---|---|---|---|
| Standard Delivery | 2-3 business days | No cut-off | Royal Mail |
| Premium Next-Day Delivery | Next business day | 3 PM weekdays | Royal Mail 24 |
Next-day delivery guarantee applies to orders approved before 3 PM to these regions:
- England
- Scotland
- Wales
- Northern Ireland
Service Restrictions: We currently cannot deliver to: Republic of Ireland, Continental Europe, USA, or Canada
Is packaging discreet?
Yes. All orders are shipped in plain, unmarked packaging via tracked courier services.
Do I need to stay home for delivery?
No. You'll receive a tracking number to monitor your parcel's progress.
Do you deliver on weekends or bank holidays?
Deliveries occur Monday–Friday only. We do not ship on weekends or UK bank holidays.
What should I do if my order hasn't arrived?
Use your tracking number to locate the parcel or contact our support team for assistance.
Can I receive delivery updates via SMS?
Yes. Provide your mobile number at checkout for courier updates. We will not use it for marketing purposes.
Credit/Debit Cards
Visa, Mastercard, Maestro, American Express
Secure 3D authentication
Bank Transfer
Select at checkout for unique reference details
Order processes once payment clears
We use SSL encryption and PCI DSS compliance to secure transactions. Learn more in our Privacy Policy.
How long do refunds take to process?
Card payments: Refunds appear in 3–5 days.
Bank transfers: We'll contact you for account details to return funds.
Why was my order declined?
Declined orders are not charged. Card authorisations release funds within 3–5 days (contact your bank for details).
Can I return prescription medication?
No. UK law prohibits returns of dispensed prescription treatments for safety reasons.
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Sildenafil FAQs
What is Sildenafil and what is it prescribed for?
Sildenafil (sildenafil citrate) is the active ingredient in Viagra, primarily prescribed to treat erectile dysfunction (ED) in men. It helps achieve and maintain erections by increasing blood flow to the penis during sexual stimulation. It's also used to treat pulmonary arterial hypertension (PAH). Note that it doesn't protect against STIs or increase sexual desire.
What types of Sildenafil are available?
Available options include:
- Generic Sildenafil - Most cost-effective option
- Sandoz Sildenafil - Features easy-split tablets
- Teva Sildenafil - Consistent brand experience
- Viagra - The original branded version
How effective is Sildenafil for ED?
Clinical studies demonstrate that Sildenafil effectively helps most men with ED achieve and maintain satisfactory erections when taken as directed with sexual stimulation.
How quickly does Sildenafil work and how long do effects last?
Sildenafil typically begins working within 30-60 minutes (sometimes as quickly as 14 minutes), with peak effectiveness around 1 hour after dosing. Effects usually last 4-6 hours, though may persist up to 10 hours in some individuals.
What is the proper dosage of Sildenafil?
Standard dosing:
- Starting dose: 50mg taken 30-60 minutes before sex
- Adjustment: May be increased to 100mg or decreased to 25mg based on response
- Maximum: 100mg per 24 hours
Never exceed the recommended dose without medical supervision.
Is Sildenafil safe to use?
Sildenafil is MHRA-approved and generally safe when used as directed. However, it can interact dangerously with certain medications (especially nitrates) and may not be suitable if you have:
- Heart problems or recent heart attack/stroke
- Severe liver or kidney disease
- Low blood pressure
- Certain eye conditions
- Sickle cell anaemia
Always consult your doctor before use.
What are the alternatives to Sildenafil?
Main ED medication alternatives:
| Medication | Onset Time | Duration | Notes |
|---|---|---|---|
| Tadalafil (Cialis) | 30 mins | Up to 36 hrs | Available as daily low-dose option |
| Vardenafil (Levitra) | 60 mins | 4-5 hrs | Similar to Sildenafil |
| Avanafil (Spedra) | 15-30 mins | 6 hrs | Fastest-acting option |
Can women or younger men take Sildenafil?
Women: Sildenafil is not approved for female use in the UK and there's no evidence it helps with female sexual dysfunction.
Younger men: Only approved for adult males (18+). Not prescribed to adolescents.
How can I reduce Sildenafil side effects?
To minimise side effects:
- Start with the lowest effective dose (25-50mg)
- Avoid alcohol and heavy meals
- Don't combine with other ED medications
- Stay properly hydrated
Consult your doctor if side effects persist or concern you.
Are there long-term effects from taking Sildenafil?
No harmful long-term effects have been identified with proper use. However:
- It's meant for as-needed use, not daily consumption (unless prescribed differently for PAH)
- Regular check-ups are recommended for ongoing treatment
- Effectiveness doesn't diminish with long-term use
Does Sildenafil increase size or stamina?
Size: No effect on penis size.
Stamina: Doesn't directly delay ejaculation, but may help maintain erections longer if premature loss of erection is an issue.
Can I drink alcohol or eat before taking Sildenafil?
Alcohol: Limit consumption as it can reduce effectiveness and increase side effects like dizziness.
Food: Heavy/fatty meals may delay absorption. Ideal to take on empty stomach or with light meal.
What if Sildenafil doesn't work for me?
If ineffective after several attempts:
- Ensure proper timing (30-60 mins before sex)
- Try without alcohol or heavy meals
- Attempt different doses (under medical supervision)
- Consider alternative ED medications if still unsuccessful
Consult your doctor if problems persist.
Is it safe to buy Sildenafil online?
Only through regulated UK pharmacies with proper prescription services. Avoid:
- Unregulated websites
- Offers without medical consultation
- Suspiciously cheap products
Legitimate online pharmacies will always require a consultation with a GP or prescriber.
Sildenafil vs Tadalafil - which is better?
| Factor | Sildenafil | Tadalafil |
|---|---|---|
| Onset Time | 30-60 mins | 30 mins-2 hrs |
| Duration | 4-6 hrs | Up to 36 hrs |
| Food Interaction | Affected by fatty meals | Less affected |
| Daily Use Option | No | Yes (2.5/5mg) |
| Visual Side Effects | More common | Less common |
Choice depends on your lifestyle and sexual habits.
What important precautions should I take with Sildenafil?
- Never combine with nitrates (heart medications) - dangerous blood pressure drop
- Avoid grapefruit juice - may increase side effects
- Seek immediate medical help if erection lasts >4 hours (priapism)
- Disclose all medications to your doctor (especially alpha-blockers or blood pressure drugs)
- Store properly at room temperature
 | Authored by Nabeel M |
Medical Content Manager & Pharmacy Associate
Nabeel is a co-founder of Chemist Doctor. He works closely with our medical team to ensure the information is accurate and up-to-date.
 | Reviewed by Usman M (2073618) |
Director & Superintendent Pharmacist
Usman is a co-founder, and superintendent pharmacist of Chemist Doctor. He leads the clinical team and online prescribing services, utilising his expertise.
Review Date: 08 May 2025
Next Review: 14 December 2025
Published on: 08 May 2025
Last Updated: 09 May 2025
Responsible Pharmacist
 | Usman Mir Superintendent GPhc: 2073618 |
We Are Regulated
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Chemist Doctor is an online pharmacy and online doctor service, owned and operated by Chem Doc Ltd (Company Reg. 16478812). Prescriptions are managed by our sister company, Inspire Pharmacy (GPhC No. 9011381), a registered pharmacy located at Unit 18, Croft Road Industrial Estate, Newcastle-under-Lyme, Staffordshire, ST5 0TW. The content on this website is for informational purposes only. It should support, not replace, advice from your healthcare provider. Always consult your doctor if you suspect a health issue or before beginning new medication. Ensure you read the leaflets provided with any medicines. For further details, visit our policies and terms & conditions at the bottom of each page.
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