Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor widely prescribed in the UK for erectile dysfunction and pulmonary arterial hypertension. A common question amongst patients concerns the correct method of administration: do you chew or swallow sildenafil tablets? The answer is straightforward—standard sildenafil tablets should always be swallowed whole with water, not chewed. This article explains why swallowing is the recommended method, what happens if tablets are chewed, and provides practical guidance on taking sildenafil safely and effectively to maximise therapeutic benefit whilst minimising risks.

How to Take Sildenafil Correctly

Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK for the treatment of erectile dysfunction and pulmonary arterial hypertension. The medication works by relaxing smooth muscle in blood vessels, thereby increasing blood flow to specific areas of the body. For erectile dysfunction, sildenafil is typically prescribed at doses of 25 mg, 50 mg, or 100 mg, with 50 mg being the standard starting dose for most men.

The correct method of administration is crucial for optimal therapeutic effect. Standard sildenafil tablets should be swallowed whole with water , approximately 1 hour before sexual activity, though some men may respond from 30 minutes onwards. Taking the medication on an empty stomach or after a light meal generally produces faster results, as high-fat meals can delay absorption and reduce peak plasma concentrations by up to 29%. The medication remains effective for up to around 4 hours, though this varies between individuals.

It is important to note that sildenafil does not cause automatic erections; sexual stimulation is required for the medication to work effectively. Patients should not take more than one dose within a 24-hour period, and the maximum recommended dose is 100 mg daily. A lower starting dose of 25 mg is recommended for patients aged 65 years or older, those with hepatic impairment, severe renal impairment, or taking certain interacting medications (such as ritonavir, where the maximum is 25 mg in 48 hours).

It's essential to understand that dosing regimens for erectile dysfunction and pulmonary arterial hypertension differ significantly, and products should not be interchanged between these indications.

Key points for correct administration include:

• Take the tablet approximately 1 hour before anticipated sexual activity

• Swallow whole with a glass of water

• Avoid high-fat meals immediately before taking sildenafil

• Do not exceed one dose per day

• Sexual stimulation is necessary for the medication to work

Do You Chew or Swallow Sildenafil Tablets?

The standard formulation of sildenafil tablets available on NHS prescription and through UK pharmacies is designed to be swallowed whole, not chewed. This is the licensed and recommended method of administration as specified by the Medicines and Healthcare products Regulatory Agency (MHRA) and detailed in the Summary of Product Characteristics (SmPC) for sildenafil products.

Chewing standard sildenafil tablets is not advised for several important reasons. The tablet coating and formulation are designed for gastrointestinal absorption, where the active ingredient is released and absorbed primarily in the small intestine. The pharmacokinetic profile—how the drug is absorbed, distributed, metabolised, and eliminated—has been established based on oral swallowing of intact tablets. Altering this method may affect the predictability of the medication's onset, duration, and overall efficacy.

Furthermore, sildenafil has a characteristic bitter taste that many patients find unpleasant. The tablet coating serves to mask this taste and facilitate comfortable swallowing. Chewing the tablet would expose the oral mucosa to this bitter flavour and could potentially cause discomfort.

Patients who have difficulty swallowing tablets should discuss this with their GP or pharmacist rather than attempting to chew the medication. The healthcare professional can provide advice on techniques to make swallowing easier or consider whether alternative formulations might be appropriate. If you are prescribed standard sildenafil tablets, always swallow them whole with water as directed by the SmPC.

Different Forms of Sildenafil Available in the UK

In the UK, sildenafil is available in several different formulations, each designed for specific patient needs and preferences. Understanding these options can help patients and healthcare professionals select the most appropriate form for individual circumstances.

Standard film-coated tablets are the most commonly prescribed form, available in 25 mg, 50 mg, and 100 mg strengths. These are designed to be swallowed whole and represent the original formulation with well-established efficacy and safety data. They are available both as the branded product Viagra and as generic sildenafil, with the generic versions being significantly more cost-effective for both the NHS and private purchasers. Viagra Connect (50 mg) is also available as a pharmacy medicine without prescription, following consultation with a pharmacist.

For pulmonary arterial hypertension (PAH), sildenafil is marketed as Revatio in 20 mg tablets. Additionally, a licensed powder for oral suspension (Revatio 10 mg/mL) exists specifically for PAH treatment in adults and children. It is important to note that PAH formulations are not licensed for erectile dysfunction, and the products should not be interchanged between indications.

Some patients may encounter unlicensed or imported formulations, including different strengths not standard in the UK. It is essential to only use sildenafil products that have been prescribed by a UK-registered healthcare professional and dispensed by a regulated pharmacy. Purchasing medications from unverified online sources carries significant risks, including receiving counterfeit products that may contain incorrect doses, contaminants, or no active ingredient at all.

What Happens If You Chew Sildenafil Tablets?

Chewing standard sildenafil tablets, whilst not the intended method of administration, is unlikely to cause serious immediate harm in most cases. However, this practice can lead to several undesirable consequences that may affect both the medication's efficacy and the patient's experience.

The medication is designed for gastrointestinal absorption after swallowing whole. There is no evidence that chewing standard sildenafil tablets improves absorption or speeds up the onset of action, and this method of administration has not been studied in clinical trials.

The most immediate consequence of chewing sildenafil is the intensely bitter taste, which many patients find extremely unpleasant. This bitterness can linger in the mouth and may cause temporary discomfort or nausea. The tablet coating is specifically designed to prevent this taste experience, and bypassing it by chewing defeats this protective function.

If chewing becomes a habitual practice, it may lead to inconsistent therapeutic responses, making it difficult for healthcare professionals to optimise dosing or assess treatment efficacy accurately.

If you have accidentally chewed a sildenafil tablet, there is generally no need for alarm. Rinse your mouth with water and continue to drink water as normal. Do not take an additional dose to compensate for perceived reduced efficacy. If you experience any unusual symptoms or side effects after taking sildenafil in any manner, contact your GP or NHS 111 for advice. You can also report suspected side effects to the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk or via the Yellow Card app).

Tips for Taking Sildenafil Safely and Effectively

Maximising the benefits of sildenafil whilst minimising potential risks requires attention to several practical considerations. Following evidence-based guidance can significantly improve treatment outcomes and patient satisfaction.

Timing and food intake are crucial factors. For optimal absorption, take sildenafil on an empty stomach or after a light meal. High-fat foods can delay absorption by up to an hour and reduce peak plasma concentrations. Plan to take the medication approximately one hour before anticipated sexual activity, allowing time for absorption and onset of action. Some men find that taking it 30 minutes beforehand is sufficient, whilst others may need the full hour.

Alcohol consumption should be limited when using sildenafil. Whilst moderate alcohol intake (one or two units) is unlikely to cause problems, excessive drinking can impair erectile function independently and may increase the risk of adverse effects such as dizziness, headache, or hypotension. The combination of alcohol and sildenafil can also lead to orthostatic hypotension (a sudden drop in blood pressure upon standing).

Drug interactions require careful consideration. Sildenafil must never be taken with:

• Nitrates (such as glyceryl trinitrate for angina) or nicorandil

• 'Poppers' (amyl nitrite)

• Riociguat (a guanylate cyclase stimulator)

These combinations can cause life-threatening hypotension. Caution is needed with alpha-blockers used for prostate problems or hypertension; ensure you are stable on alpha-blocker therapy before starting sildenafil, begin with 25 mg, and consider separating doses. Strong CYP3A4 inhibitors (such as ketoconazole, itraconazole, erythromycin, clarithromycin) and HIV protease inhibitors (especially ritonavir, where the maximum is 25 mg in 48 hours) can increase sildenafil levels. Grapefruit juice should also be avoided. Always inform your GP and pharmacist of all medications you are taking, including over-the-counter products and herbal supplements.

Common side effects include headache, flushing, indigestion, nasal congestion, and dizziness. Always read the patient information leaflet for a complete list.

Important safety points include:

• Store tablets in their original packaging at room temperature

• Check the expiry date before use

• Never share your medication with others

• Seek immediate medical attention if you experience an erection lasting more than four hours (priapism)

• If you develop sudden vision or hearing loss, stop taking sildenafil and seek urgent medical attention

• If you experience chest pain, seek urgent help and inform healthcare providers about your sildenafil use (nitrates should be avoided)

• Do not purchase sildenafil from unregulated online sources

When to seek medical advice: If sildenafil is not effective after several attempts at the maximum prescribed dose, contact your GP rather than increasing the dose yourself. Lack of response may indicate underlying health conditions requiring investigation, such as cardiovascular disease, diabetes, or hormonal imbalances. NICE guidance recommends that men with erectile dysfunction should receive a comprehensive cardiovascular risk assessment, as erectile dysfunction can be an early marker of cardiovascular disease. Your GP can arrange appropriate investigations and may refer you to specialist services if needed.

Frequently Asked Questions