For many, starting an ED medication means increasing or returning to sexual activity. With that comes the positive aspects of sexual intimacy. However, it also comes with potentially uncomfortable conversations about sexually transmitted infections. Sharing your STI status is an important part of allowing your partner to make a truly informed decision about having sex.

If you have a sexually transmitted infection, you must inform any potential sexual partner. Moreover, this should be done before engaging in any activity that risks giving them an infection. It is also important to ask any prospective partner about their status. Lastly, while condoms are helpful in reducing the risk of pregnancy, transmitting, or acquiring an infection, they can never be 100% effective. That is why informed consent is such an important part of sharing sexual intimacy with honesty and clarity.

There are hundreds of medications that can interact with Viagra. Most are not severe but some can be life threatening, as with any nitrates, nitrites, or nitroglycerin. Even simple over the counter medications should be checked for interactions. Remember, something as safe as grapefruit can alter how your body handles Viagra. All your providers should be kept informed of any medication that is added, dropped, or changed in your regimen.

The Physician Desk Reference (PDR) lists the medications that can interact with Viagra, along with the contraindications to its use. The PDR is included because it is comprehensive and must be read in its entirety. Contraindications can be absolute, as with nitrates/nitrites, act as relative warnings about drug interactions, and inform patients and healthcare providers how certain conditions can affect the metabolism of sildenafil, either increasing or decreasing the amount in the blood. A few relevant sections are summarized below concerning contraindications and drug interactions, but it is not a complete overview. Please, read the entire package insert, as well.

General Information

It should not be used in anyone allergic to any of the components used to make Viagra tablets. Also, as discussed above, the use of multiple phosphodiesterase inhibitors at the same time, is not recommended. It has not been studied.

The use of Viagra is not recommended in patients with Pulmonary Veno-Occlusive Disease (PVOD).

Nitrate/Nitrite Therapy

ABSOLUTELY no one should take Viagra (sildenafil) if they “are currently on nitrate/nitrite therapy.” That includes even if the patient uses of nitrates/nitrite therapy intermittently. Also, no one who uses recreational nitrates/nitrites (poppers, etc.) should use Viagra (sildenafil).

Geriatric (The Elderly), Hepatic (Liver) Disease, Renal (Kidney) Impairment

Viagra is metabolized by a complex system that can be compromised in the elderly, or in patients who suffer from liver disease, or in those whose kidney function is reduced by illness or age. Therefore, it is recommended “not to exceed a maximum single dose of 25 mg sildenafil in a 48 hour period.”

Moreover, certain drugs have a dramatic effect on the metabolism of Viagra (sildenafil) similarly increasing the blood level dramatically. Therefore, those taking erythromycin, itraconazole, ketoconazole, saquinavir, and ritonavir should follow the same regimen.

Angina (Chest Pain), Aortic Stenosis, Cardiac Arrhythmias (Irregular Heartbeats), Cardiac Disease (Heart Disease), Coronary Artery Disease (Narrowing of the Heart Arteries), Heart Failure, Hypertension (High Blood Pressure), Hypotension (Low Blood Pressure), IHSS (Idiopathic Hypertrophic Subaortic Stenosis–a Heart Defect), Myocardial Infarction (Heart Attack), Stroke (like a heart attack but affecting the brain)

“There is a degree of cardiac risk associated with sexual activity; therefore, prescribers, should evaluate the cardiovascular status of their patients prior to initiating any treatment for erectile dysfunction.” [NOTE: This means that if you and your provider have a reason to believe after diagnosing erectile dysfunction that you are not healthy enough for sex, you shouldn’t use anything that will help you have sex until you are healthier. Your doctor counts on an honest answer about your health and your capacity to be sexually active. It may seem overly cautious but think about it; if you aren’t healthy enough for sex, shouldn’t you take care of your health before trying to regain your sex life? There have been more than 75 deaths due to cardiac events “reported in association with sildenafil use.” It may not seem like many deaths but you don’t want to be the person who bumps that number over 100.]

The PDR advises that “caution should be used if Viagra (sildenafil) is prescribed in the following groups: patients who have suffered a myocardial infarct, stroke, or life threatening arrhythmias in the last 6 months; patients with resting hypotension (BP<90/50) or resting hypertension (BP>170/100); patients with fluid depletion; patients with cardiac disease, heart failure, or coronary artery disease which causes unstable angina.”

The PDR notes that the American College of Cardiology recommends that sildenafil be used in caution with patients (not on nitrates, of course) with active coronary ischemia, meaning they have blocked heart arteries that is compromising the function of their heart, such as would show by having symptoms like chest pain or by failing a stress test. They also advise caution in anyone with low blood pressure or low blood volume or in anyone with high blood pressure on a “complicated, multidrug, antihypertensive program.”

Patients with “Left Ventricular Outflow Obstruction (e.g., aortic stenosis, idiopathic hypertrophic subaortic stenosis)” should be approached with caution as they, and patients with poor control of the swings in their blood pressure, can be very sensitive to sildenafil and other vasodilators (drugs that open up the blood vessels). They also recommend that doses of Viagra (sildenafil) over 25 mg not be given within 4 hours of taking an alpha-blocker (e.g. doxazosin).

Leukemia, Multiple Myeloma, Penile Structural Abnormality, Polycythemia, Priapism, Sickle Cell Disease

Priapism is an erection lasting more than 4 hours and it can occur with the use of Viagra (sildenafil). Priapism can be painful but, with or without pain, an erection that lasts over 4 hours could result in damage to the tissues of the penis. People with the above conditions are at greater risk of suffering from priapism with the use of sildenafil. The PDR states, “sildenafil and other agents for the treatment of erectile dysfunction, should be used with caution in patients with penile structural abnormality (such as angulation, cavernosal fibrosis, or Peyronie’s disease), or in patients who have conditions which may predispose them to priapism (such as sickle cell disease, leukemia, multiple myeloma, polycythemia, or history of priapism).”

Human Immunodeficiency Virus (HIV) Infection

The PDR states, “Patients should be reminded that Viagra, when used for erectile dysfunction, offers no protection against sexually transmitted disease.”

Coagulopathy (Bleeding Abnormalities), Peptic Ulcer Disease (Stomach Ulcer)

There is no safety information yet accumulated on how Viagra (sildenafil) affects patients with bleeding disorders or active stomach ulcers so caution is recommended.

Gastroesophageal Reflux Disease (GERD–heartburn due to reflux of acid), Hiatal Hernia (part of stomach slips upward through the diaphragm)

Viagra (sildenafil) decreases the pressure of the valve that stops acid from coming back up from the stomach and into the esophagus. It also inhibits the movement of the esophagus itself. It could make symptoms worse for people with GERD or a hiatal hernia so it is recommended that it be used with caution in these patients.

Non-arteritic Anterior Ischemic Optic Neuropathy (NAION), Retinitis Pigmentosa, Visual Disturbance

The PDR states, “Use sildenafil cautiously in patients with preexisting visual disturbance. Post-marketing reports of sudden vision loss have occurred with phosphodiesterase inhibitors. Vision loss is attributed to a condition known as non-arteritic anterior ischemic optic neuropathy (NAION), where blood flow is blocked to the optic nerve. Patients with a history of NAION are at increased risk for recurrence. Only use a PDE5 inhibitor in these individuals if the anticipated benefit outweighs the risk.” It is never recommended for patients with known hereditary degenerative retinal disorders, including retinitis pigmentosa.

There are other situations that would give a healthcare provider pause. Some would be if you have lightheadedness, fainting spells, leg cramping when you walk, inability to climb stairs or walk a few blocks without getting short of breath, or if you have allergies to any of the other phosphodiesterases or their components. These, and any other symptoms, must be discussed.

A Special Warning for Pilots and Air Traffic Controllers

Some people experience visual side effects when taking PDE5 inhibitors for erectile dysfunction. Due to the sensitive nature of their work, pilots and air traffic controllers should not take Viagra or sildenafil within 6 hours of aviation related duties. Cialis (tadalafil) is a much longer acting medication. Pilots and air traffic controllers should not take Cialis within 36 hours of aviation related duties. Daily Cialis use, at any dose, is not an option for men with these professions.

The list below is long and not one drug on the list is meaningless. That is why we need to know every drug you take and every healthcare provider needs to know you take Viagra (sildenafil).

Note: Some medications are not on the list but are included in the PDR, which is why it must be read as well. In addition, the list changes as medications may be added over time.

• Alfuzosin (Uroxatral) (Treats High Blood Pressure or Enlarged Prostate)

• Aliskiren (Tekturna, Rasilez) (Treats High Blood Pressure)

• Alpha-blockers (e.g., Cardura, Coreg Flomax, Hytrin, Minipress, Oravase, Rapaflo, Regitine,Trandate) (Treats High Blood Pressure or Enlarged Prostate)

• Ambrisentan (Letairis) (Treats PAH–High Blood Pressure in the Arteries of the Lungs)

• Amlodipine (Norvasc) (Treats High Blood Pressure)

• Amprenavir (Agenerase) (Treats HIV)

• Amyl Nitrite (Amyl nitrite Systemic, Poppers, Rush) (Recreational Drug)

• Aprepitant (Emend) (Treats Nausea)

• Atazanavir (Reyataz) (Treats HIV)

• Atropine (Isopto Atropine) (Treats Eye Conditions)

• Boceprevir (Pegasys, Pegintron) (Treats PAH and Hepatitis C)

• Butyl Nitrate (Poppers, Rush, Liquid Gold) (It is a recreational drug)

• Brigatinib (Alunbrig) (Cancer)

• Capecitabine (Xeloda) (Cancer)

• Cariprazine (Vraylar) (Psychiatric Disorders)

• Ceritinib (Zykadia) (Cancer)

• Cimetidine (Tagamet) (Stomach Ulcers)

• Ciprofloxacin (Proquin, Cipro) (Antibiotic)

• Clarithromycin (Biaxin) (Antibiotic)

• Clopidogrel (Plavix) (Blood Thinner)

• Cobicistat (Stribild, Tybost) (Treats HIV)

• Conivaptan (Vaprisol) (Treats Low Sodium in the blood)

• Crizotinib (Xalkori) (Cancer)

• Darunavir (Prezista) (Treats HIV)

• Dasabuvir (Viekira XR, Viekira Pak–contains Ritonavir*) (Treats Hepatitis C)

• Delavirdine (Treats HIV)

• Dihydroergotamine (Migranal) (Treats Migraines)

• Diltiazem (e.g., Cartia, Cardizem, Dilacor XR, Tiazac,) (Treats High Blood Pressure)

• Doxazosin (Cardura, Carduran) (Treats High Blood Pressure or Enlarged Prostate)

• Dronedarone (Multaq) (Irregular Heartbeats)

• Duloxetine (Cymbalta) (Treats Depression and certain nerve pain disorders)

• Erythromycin (Erythrocin, Ery-Tab, E-Mycin, Eryc) (Antibiotic)

• Fluconazole (Diflucan) (Treats Fungal and Yeast Infections)

• Fluoxetine (e.g., Prozac, Sarafem) (Treats Psychiatric disorders like depression)

• Fluvoxamine (Faverin, Fevarin, Floxyfral, Dumyrox, Luvox) (Treats OCD)

• Fosamprenavir (Lexiva) (Treats HIV)

• Grapefruit juice

• Idelalisib (Zydelig) (Treats Cancer–Leukemia)

• Imatinib (Gleevec) (Treats Cancer–Leukemia)

• Indinavir (Crixivan) (Treats HIV)

• Isavuconazonium (Cresemba) (Treats Fungal Infections)

• Isocarboxazid (Marplan) (Treats Depression)

• Isosorbide Dinitrate or Monohydrate (Isordil Titradose, Dilatrate-SR, Imdur, Imdur ER, Ismo, Monoket, IsoDitrate) (Treats Heart Disease and Chest Pain)

• Itraconazole (Sporanox, Onmel) (Treats Fungus and Yeast)

• Ivacaftor (Kalydeco) (Treats Cystic Fibrosis)

• Ketoconazole (Nizoral, Extina, Ketodan Kit, Kuric, Nizoral A-D, Xolegel) (Treats Fungal Infections)

• Lopinavir; Ritonavir (Kaletra) (Contains Ritonavir and Treats HIV)

• Lorcaserin (Belviq) (Weight Control)

• Lurasidone (Latuda) (Treats Depression)

• Mifepristone, RU-486 (Korlym, Mifeprex) (Treats Cushing’s Syndrome and Ends Pregnancy)

• Mitotane (Lysodren) (Treats Cancer and Cushing’s Syndrome)

• Monoamine oxidase inhibitors (e.g., Azilect, Marplan, Nardil, Parnate) (Treats Depression)

• Nebivolol (Bystolic) (Treats High Blood Pressure)

• Nelfinavir (Viracept) (Treats HIV)

• Nesiritide (Natrecor) (Treats Heart Failure but is an IV drug)

• Netupitant (Akynzeo) (Prevents Nausea and Vomiting)

• Nifedipine (Procardia, Nifedical XL, Adalat, Procardia XL) (Heart Disease among others)

• Nilotinib (Tasigna) (Treats Cancer–Leukemia)

• Nitrates (Isordil Titradose, Dilatrate-SR, Imdur, Imdur ER, Ismo, Monoket, IsoDitrate) (Treats Heart Disease and Chest Pain)

• Nitroglycerin (Nitro-bid, Nitrocot SA Capsule, Nitro-dur, Nitrostat, Nitrodisc, Nitrek transdermal, Minitran, Nitrol ointment, Transderm-Nitro, Nitro-Time, Nitrotab, NitroMist, Nitro-Par, Nitrolingual, Nitroquick, Transderm-Nitro, Nitrogard, Nitroglyn, Nitrong) (Treats Chest Pain and Heart Conditions)

• Nitroprusside (Nipride RTU, Nitropress) (Heart Failure and High Blood Pressure)

• Ombitasvir; Paritaprevir; Ritonavir (Technivie, Viekira Pak) (Treat Hepatitis C)

• Phenoxybenzamine (Dibenzyline) (Treat High Blood Pressure and Pheochromocytoma)

• Phentolamine (Regitine, Oraverse) (Erectile Dysfunction, High Blood Pressure)

• Phenylephrine (e.g.,Sudafed) (Decongestant)

• Posaconazole (Noxafil) (Treats Fungal Infections)

• Prazosin (e.g., Minipress, Vasoflex, Lentopres, Hypovase) (Treats High Blood Pressure, PTSD, and Anxiety)

• Ribociclib (Kisqali) (Treats Cancer)

• Riociguat (Adempas) (Treats High Blood Pressure in the Arteries of the Lung)

• Ritonavir (Norvir) (Also found in Technivie and Viekira Pak) (Treats HIV and Hepatitis C)

• Sapropterin (Kuvan) (Treats a disorder that causes amino acid buildup in the brain)

• Saquinavir (Invirase, Fortovase) (Treats HIV)

• Silodosin (Rapaflo) (Treats an Enlarged Prostate)

• Tacrolimus (Prograft, Advagraf XL, Protopic, Hecoria) (Treats Organ Transplants)

• Tamsulosin (Flomax) (Treats an Enlarged Prostate)

• Telaprevir (Incivek, Incivo) (Treats Hepatitis C)

• Telithromycin (Ketek, Ketek Pak) (Antibiotic)

• Telotristat Ethyl (Xermelo) (Treats diarrhea in cancer patients)

• Terazosin (Hytrin) (Treats High Blood Pressure)

• Tipranavir (Aptivus) (Treats HIV)

• Verapamil (Calan, Isoptin) (Treats High Blood Pressure, Angina, Irregular Heart Beats)

• Vigabatrin (Sabril) (Treats Seizure Disorders)

• Voriconazole (Vfend) (Treats Fungal Infections)

The side effects of sildenafil (Viagra) are typically mild. Common side effects can include: 

• Headache -  ED medications can cause headaches by widening blood vessels and increasing blood flow, but these are usually mild and ease as the medication wears off (about 4 hours) and with continued use. To help:

  • Drink more water to reduce headache intensity.

  • Take over-the-counter Tylenol or Motrin 1 hour before your medication to lessen or prevent headaches.

• Indigestion/heartburn -  Heartburn is a common side effect of ED medications, affecting about 1 in 10 patients. To help:

  • Limit caffeine and avoid trigger foods (acidic, spicy, or alcohol) before taking your medication.

  • Drink plenty of water.

  • Avoid eating 2 hours before bed and elevate your head while sleeping.

  • Try over-the-counter remedies like Tums.

• Flushing or redness/warmth in the face - This is a common side effect of ED medications, caused by increased blood flow and dilation of blood vessels, including those in your skin. While it may result in a red, flushed appearance, it’s not dangerous and can even indicate the medication is working. To help:

  • Use a cold compress on your face.

  • Keep the room cool by opening a window or using a fan.

• Stuffy or runny nose - This side effect tends to fade within a few hours of using the medication. To help:

  • Use an over-the-counter nasal spray like Flonase when you take your medication to prevent congestion.

  • Take a warm shower after your dose; the steam can help relieve congestion.

• Lightheadedness or dizziness - Lightheadedness can happen due to a decrease in your blood pressure. Severe or persistent lightheadedness, and especially fainting, can be dangerous and should be evaluated in person. To help mild lightheadedness

  • Lie down until the sensation passes and stand up slowly.

  • Stay hydrated by drinking water.

  • If you take blood pressure medication, avoid taking it at the same time as your ED medication.

• Back pain or muscle aches - Muscle aches and back pain may appear 12-24 hours after taking the medication and go away as the medication wears off. To help:

  • Drink more water to reduce their intensity.

  • Take an over-the-counter pain reliever, like Tylenol or Motrin, 1 hour before your ED medication to lessen or prevent discomfort.

If you experience any of these common side effects and find them to be persistent, bothersome, or preventing you from taking your medication, please reach out to your Ro-affiliated healthcare provider.  

Rare side effects of sildenafil can include: 

• An erection that lasts longer than four hours and won’t go away (priapism).

• Sudden loss of vision

• Sudden loss or decrease/change in hearing

• Chest pain or shortness of breath

• Fainting

If you experience any of these symptoms, stop your medication and seek immediate medical attention. If you experience a sudden loss of vision or a decrease/change in hearing, your evaluation must include a vision and/or hearing test and possibly a specialist evaluation by a vision (ophthalmologist or optometrist, or hearing specialist (ENT/audiologist)).

Rarely, patients using sildenafil may experience blue-tinged vision. This is not typically dangerous, but if you experience changes to your vision, stop using your medication and make an appointment with an ophthalmologist. 

IMPORTANT: Please report any side effects you experience to your Ro-affiliated healthcare provider. This list is not exhaustive. A complete list of side effects can be found here.  If you are experiencing a medical emergency, seek immediate medical attention or call 9-1-1. Symptoms such as chest pain, shortness of breath, severe headache, fainting, visual changes, hearing loss, or any other severe side effect warrant a visit to the emergency room.