Sildenafil in Singapore How it works, dosage and side effects

Sildenafil is a prescription medicine for erectile dysfunction (ED). This guide explains how it works, how to take it, how long it lasts, its side effects and who shouldn't take it.

Medically reviewed Based on clinical evidence Benefits and risks

Sildenafil at a glance

Type of medicine: PDE5 inhibitor
Used for: Erectile dysfunction
When to take it: About 1 hour before sex
Works best: 1–2 hours after
Usual starting dose: 50 mg
Maximum: One dose a day
Availability: Prescription-only

Information reviewed by: Dr Lye Tong Fong, MBBS (S'pore)

Last updated: Oct 25, 2026

What Is Sildenafil and How Does It Work?

Sildenafil (sildenafil citrate) is a prescription medicine used to treat erectile dysfunction (ED) in men. It belongs to a group of medicines called PDE5 inhibitors, which help increase blood flow to the penis during sexual arousal.^1,2

It blocks an enzyme called phosphodiesterase type 5 (PDE5), so the blood vessels in the penis can relax and widen when you're aroused:

1 · ArousalSexual stimulation starts the natural signal for an erection.

2 · Blood vessels relaxSildenafil blocks PDE5, so the vessels stay relaxed for longer.

3 · Blood flowMore blood can flow into the penis, which helps an erection.

It isn't an aphrodisiac. Sildenafil doesn't cause an erection on its own or increase sex drive — sexual stimulation is still needed.

Sildenafil Price in Singapore

Sildenafil typically costs from $9 per tablet, depending on whether you choose a branded or a generic version. A consultation fee may apply on top, so confirm the total with the clinic before you begin.

ED medicines are generally not claimable under MediSave, and most insurance plans exclude them.

How to Take Sildenafil

~1 hourUsual time to take it before sex

1–2 hoursWhen it works best

Up to ~4 hoursA weaker effect may last this long

Swallow the tablet whole with water, usually about 1 hour before sex — it can be taken anywhere from 30 minutes to 4 hours beforehand.^2,3
You can take it with or without food, but a heavy or fatty meal may delay how quickly it starts working.
Take no more than one dose a day.
Avoid heavy drinking: it can make it harder to get an erection and increases the chance of dizziness or fainting. Light-to-moderate alcohol doesn't appear to add significant risk.
The usual starting dose is 50 mg. Your doctor may adjust it between 25 mg and 100 mg, depending on how well it works and how you tolerate it. 100 mg is the maximum dose.

If it doesn't work the first time, don't give up — many men need several attempts, and sometimes a dose adjustment, before it works well. Talk to your doctor if it hasn't worked after a few tries, rather than changing the dose yourself.⁴

Questions about erectile dysfunction? A doctor can help.

Speak to a Doctor

Who Should Not Take Sildenafil?

A doctor checks your health and every medicine you take before prescribing it. Sildenafil is not suitable for everyone:^2,3

Must not take it

Take nitrates (e.g. glyceryl trinitrate or isosorbide for chest pain), or use “poppers”
Take riociguat
Have had a recent heart attack or stroke
Have very low blood pressure
Have been told to avoid sexual activity for heart reasons

Discuss carefully with your doctor if you

Have severe liver problems
Have lost sight in one eye from reduced blood flow to the optic nerve (NAION), or have an inherited eye condition such as retinitis pigmentosa
Take alpha-blockers (e.g. for the prostate)
Take certain antifungal, antibiotic or HIV medicines (e.g. ketoconazole, itraconazole, erythromycin or HIV protease inhibitors) — these raise sildenafil levels, so a lower dose is often needed
Have kidney problems
Have a bleeding disorder or a stomach ulcer
Have sickle cell anaemia, leukaemia or multiple myeloma
Have a curved or scarred penis (e.g. Peyronie's disease)

Sildenafil Side Effects

Common — usually mild

Headache Flushing Indigestion Blocked nose Dizziness Blurred or blue-tinted vision

These usually wear off within a few hours.^2,3

Get urgent medical help if you have

An erection lasting more than 4 hours
Chest pain during or after sex
Sudden loss of vision or hearing
Swelling, rash or difficulty breathing (allergy)

Not a complete list — your doctor will go through the risks with you.

Where to Get Sildenafil in Singapore

Sildenafil is a prescription-only medicine in Singapore, so it can only be obtained after a consultation with a doctor:

A doctor can prescribe it after a consultation at a clinic or hospital, or by video consultation.
Some clinics dispense it directly; others give you a prescription to fill at a pharmacy.
Pharmacies such as Watsons or Guardian can only supply it with a valid prescription — it isn't sold over the counter.
Avoid online sellers and overseas websites that sell it without a prescription: the tablets may be counterfeit, contaminated or the wrong strength.

ED is often about more than one tablet. Erections depend on blood flow, nerves, hormones and your state of mind, so ED can be linked to stress, relationship issues, smoking, alcohol, some medicines or your general health. That's why a doctor will usually ask about your overall health, not just prescribe a medicine.

Speak to a Doctor About Erectile Dysfunction

ED is common, and doctors talk about it every day. A doctor can look at the possible causes and the options that may suit you, in confidence.

Speak to a Doctor Find a Clinic

Frequently Asked Questions

What are the other names of sildenafil?

Sildenafil is also commonly known as Viagra in Singapore. Sildenafil is the name of the active ingredient.

How much does sildenafil cost in Singapore?

The cost depends on the strength, the number of tablets and where it is prescribed, and a consultation fee may apply. Ask the clinic to confirm the full cost before you start. ED medicines are generally not claimable under MediSave.

Do I need a prescription for sildenafil in Singapore?

Yes. Sildenafil is a prescription-only medicine in Singapore, so a doctor needs to check that it's safe for you first — especially your heart health and any other medicines you take.

Can I buy sildenafil online in Singapore?

Only with a doctor's prescription. In Singapore, a doctor can assess you by video consultation and prescribe sildenafil if it's suitable. Avoid online sellers and overseas websites that sell it without a prescription: the tablets may be counterfeit, contaminated or the wrong strength.

Can I buy sildenafil at a pharmacy like Watsons or Guardian?

Not over the counter. Pharmacies can only supply sildenafil with a valid doctor's prescription, so you'll need to see a doctor first.

Should I take sildenafil 50 mg or 100 mg, and how much is too much?

Most men start on 50 mg. Your doctor may raise it to 100 mg or lower it to 25 mg, depending on how well it works and how you tolerate it. The maximum is 100 mg once a day — don't take 200 mg. Taking more than the dose your doctor prescribes does not improve results and increases the risk of side effects, so don't change it yourself.

How long does sildenafil last, and how quickly does it work?

Sildenafil works best in the first 1 to 2 hours, and a weaker effect may continue for up to about 4 hours. It usually starts working within 30 to 60 minutes. A heavy or fatty meal may delay how quickly it starts working.

Can I drink alcohol with sildenafil?

Light-to-moderate drinking doesn't appear to add significant risk with sildenafil. Heavy drinking should be avoided: it can make it harder to get an erection and increases the chance of dizziness or fainting.

Is a consultation about erectile dysfunction confidential?

Yes. Medical consultations and records are confidential, and ED is a common concern that doctors discuss every day.

This page is general information and does not replace medical advice. Sildenafil is a prescription-only medicine; a doctor will assess whether it is suitable for you. Results vary between individuals.