PDE5 inhibitors have a strong safety record. Sildenafil has been on the market since 1998, taken by tens of millions of men. Side effects are common but usually mild. Serious problems are rare and almost always avoidable if you tell your doctor about your other medical conditions and medications honestly.

That is the headline. Here is the detail.

Common Side Effects

These affect anywhere from 1 in 10 to 1 in 100 men at standard doses. They are usually mild and resolve within hours.

  • Headache. The most common side effect. Often mild and short lived. Reducing the dose helps.
  • Facial flushing. Warm or pink face. Harmless.
  • Blocked or runny nose.
  • Indigestion or heartburn.
  • Dizziness, particularly on standing.
  • Back pain or muscle aches. More common with tadalafil because of how it acts on muscle PDE.
  • Mild visual changes. Bluish tint to vision or light sensitivity, mainly with sildenafil. Resolves as the drug wears off.

Most men who continue treatment find that side effects either fade with time or are easily managed by adjusting dose or switching medication.

Less Common Side Effects

  • Prolonged or painful erection (priapism)
  • Sudden change in hearing or hearing loss (rare)
  • Sudden change in vision (very rare)
  • Significant drop in blood pressure
  • Allergic reaction

If any of these occur, stop the medication and seek medical attention.

Priapism is a medical emergency A painful erection lasting more than four hours can cause permanent damage to penile tissue. Go to the nearest emergency department immediately. Do not wait it out.

The Big One: Never Mix With Nitrates

This is the one thing you must remember from this page. PDE5 inhibitors should never be used with nitrate medication. The combination can cause a dangerous, sometimes fatal, drop in blood pressure.

Nitrates are commonly prescribed for angina, chest pain, and certain heart conditions. Names to watch for include:

  • Glyceryl trinitrate (also called GTN, nitroglycerin)
  • Isosorbide mononitrate
  • Isosorbide dinitrate
  • Amyl nitrate or amyl nitrite (sometimes used recreationally as 'poppers')

If you are on any of these, PDE5 inhibitors are off the table. Tell the consulting doctor. There are alternative ED treatments that do not interact with nitrates.

Poppers and ED tablets are dangerous together Amyl nitrate or similar inhaled 'poppers' are nitrates. Combining them with sildenafil, tadalafil, or vardenafil has caused serious cardiovascular events. Do not mix them.

Other Drug Interactions

Several other medication classes interact with PDE5 inhibitors and need consideration. Not all of them are absolute contraindications. Some just need dose adjustment or extra caution.

  • Alpha blockers (used for prostate enlargement and some blood pressure conditions, e.g. tamsulosin, doxazosin). Can cause low blood pressure when combined. Manageable with dose adjustment and timing.
  • Some HIV medications (protease inhibitors like ritonavir). Increase blood levels of PDE5 inhibitors significantly. Lower starting doses are used.
  • Some antifungals (ketoconazole, itraconazole). Same issue.
  • Some antibiotics (clarithromycin, erythromycin). Same issue.
  • Riociguat (used for pulmonary hypertension). Should not be combined with PDE5 inhibitors.
  • Grapefruit juice in large quantities can mildly increase blood levels.

Always tell the consulting doctor about every medication you are taking, including over the counter remedies and supplements.

Get A Safe Assessment

An online consultation works through your medical history and current medications to ensure ED treatment is safe for you.

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When PDE5 Inhibitors May Not Be Suitable

The doctor will avoid prescribing or will use them with extra care if you have:

  • Recent heart attack or stroke (usually within 6 months)
  • Unstable or severe angina
  • Severe heart failure
  • Uncontrolled high or low blood pressure
  • Severe liver disease
  • Severe kidney disease
  • A rare eye condition called non-arteritic anterior ischaemic optic neuropathy (NAION)
  • Certain types of inherited eye disease (retinitis pigmentosa)
  • Sickle cell disease
  • A history of priapism

Many of these are not absolute. Stable, well controlled conditions may be fine. The point is that they need to be flagged at the consultation.

Alcohol

You do not need to be sober to take ED medication. A glass or two of wine is unlikely to make a meaningful difference. Heavy drinking is a different story. Alcohol is a CNS depressant and a vasodilator, both of which reduce erectile response and increase the risk of dizziness or headache. If your medication is not working as well as you hoped, alcohol is one of the first things to check.

Recreational Drug Interactions

A few notes for completeness, because honesty matters here.

  • Poppers (amyl nitrate). Do not mix. Genuinely dangerous.
  • Cocaine and methamphetamine. Both cause vasoconstriction and cardiovascular stress. Combining with PDE5 inhibitors stresses the heart further. Avoid.
  • MDMA. Can interact in similar ways. Increased cardiovascular risk.
  • Cannabis. No major direct interaction known but can affect arousal and blood pressure mildly.

Long Term Safety

PDE5 inhibitors have been used for over 25 years. Long term data is reassuring. There is no evidence they cause heart problems, cancer, or fertility issues when used as prescribed. Some men take them daily or near daily for years without difficulty.

How To Reduce Side Effects

  • Start at a lower dose if possible
  • Take with water, not heavy meals
  • Stay hydrated
  • Limit alcohol
  • Switch medication if side effects on one are not tolerated. Different PDE5 inhibitors suit different men.

Related Reading

Frequently Asked

Headache, facial flushing, indigestion, blocked nose, and dizziness. Most are mild and go away within a few hours. Tadalafil can also cause back pain or muscle aches.

It depends on the specific condition. Stable, controlled cardiovascular disease is usually fine. Active angina or severe heart failure is not. A consultation is essential. Never combine PDE5 inhibitors with nitrate medication.

Light drinking is generally fine. Heavy drinking blunts the effect and increases side effects like headache and dizziness. Heavy alcohol is one of the most common reasons for medication not working.

A painful erection lasting more than four hours. Rare but a genuine medical emergency. Permanent damage can result if it is not treated within hours. Go to the nearest emergency room.

No. PDE5 inhibitors have been used for decades and have a strong long term safety record in suitable patients. Some are even used in the treatment of pulmonary hypertension.