Safety Information
Where the hard lines are, what usually happens in the first few doses, and the three signs that mean stop and call for help.
Never combine this with nitrates
Nitroglycerin tablets, sprays, patches and ointments, isosorbide in any form, and recreational nitrites sold as poppers. The combination can produce a sudden and dangerous fall in blood pressure. No dose adjustment makes it acceptable and no interval makes it safe on the same day.
Who should not take it at all
- Anyone using nitrate medicine or recreational nitrites
- Anyone taking riociguat or a similar soluble guanylate cyclase stimulator
- Men who have had a heart attack or stroke within the last six months
- Unstable angina, or angina brought on by sexual activity
- Blood pressure that is very high or very low and not under control
- Severe liver impairment or severe kidney impairment
- A previous episode of non-arteritic anterior ischaemic optic neuropathy
- Hereditary degenerative retinal disorders such as retinitis pigmentosa
- Anyone under 18, and anyone it was not prescribed for
Mention these even if they seem unrelated
Alpha-blockers for blood pressure or prostate symptoms. Any other treatment for erectile dysfunction or pulmonary hypertension. Antifungals such as ketoconazole and itraconazole. Certain antibiotics including clarithromycin and erythromycin. HIV protease inhibitors. Some seizure medicines. Grapefruit juice in quantity. And any supplement marketed for performance, because regulators repeatedly find undeclared prescription drugs in that category.
Side effects, in order of how often they appear
Common and usually brief. Headache, facial flushing, a blocked or runny nose, mild indigestion, light-headedness on standing. These come from the same vasodilation the medicine produces elsewhere in the body and generally fade over the first few uses.
Less common. Back or muscle ache, blurred vision, temporary sensitivity to light, a blue tinge to colour vision, dry mouth.
Rare but serious. An erection persisting beyond four hours. Sudden loss or reduction of vision in one or both eyes. Sudden hearing loss, with or without ringing and dizziness. Chest pain during or shortly after sex.
Three symptoms that mean stop and get help now
An erection lasting more than four hours. A sudden change in vision or hearing. Chest pain during sexual activity. Do not wait to see whether any of them passes — call 911 or get to an emergency department.
Sensible practice
- One dose in 24 hours, no exceptions and no top-ups
- Under the tongue, fully dissolved — never chewed, never swallowed whole
- Keep drinking light; heavy intake blunts the effect and sharpens side effects
- Store it in its original packaging, away from heat and damp, out of reach of children
- Never share it — it was prescribed against your history, not anyone else's
- Tell any other clinician treating you that you take it, particularly before surgery
The question underneath the symptom
Erectile difficulty frequently appears before a cardiovascular diagnosis, sometimes by several years. The arteries involved are among the narrowest in the body, so they register vascular change early. Treating the symptom does not treat that. Know your blood pressure, your fasting glucose and your lipid panel, and take the symptom to your own doctor as information rather than an embarrassment.
Safety questions
Often, but it depends entirely which one. Nitrates are an absolute no. Some alpha-blockers need doses separated in time. List everything on the health form and let the physician decide.
That is precisely the question the review exists to answer, and it depends on the condition. Sex is exertion; if you have been advised to limit exertion, discuss this with your cardiologist first.
Common early on and it usually settles. Water helps. If it persists, ask about a lower strength rather than quietly stopping, because the dose is adjustable.
You multiply the side effects and gain very little. Never exceed one dose in 24 hours, and never take a second because the first felt slow.
Cleared it with yourself?
The prescribing physician makes the final call, and they need your full list.
Your next step
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