Sildenafil

What is this medication for?

• Pulmonary arterial high blood pressure (adjunct)

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

• Never combine with nitrate-containing therapies — this is a hard, well-documented contraindication.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Cutaneous flushing (inguinal area) (Reported)
• stomach/intestinal effects (Possible)
• Hypotension (Dose/combination-related)

Worth a phone call to your veterinarian

• Any new symptom that worries you.

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Trouble breathing, collapse, seizures, severe vomiting or diarrhea, facial swelling, or pale gums

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Concurrent nitrates (nitroglycerin, isosorbide) or nitroprusside — life-threatening low blood pressure risk
• has or has had: Pulmonary veno-occlusive disease (may worsen); resting low blood pressure, fluid depletion, severe LV outflow obstruction, autonomic dysfunction

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • Nitrates/nitroprusside
  • Azole antifungals (ketoconazole, itraconazole), erythromycin/clarithromycin, cimetidine
  • Alpha-blockers, amlodipine, other antihypertensives
  • Phenobarbital, rifampin
  • Pimobendan

Storage and handling

Room temperature, tightly sealed, protect from light.

Good to know

• Set owner expectations about cost and the experimental/extrapolated nature of veterinary dosing — human erectile-dysfunction formulations are what's typically dispensed, and no veterinary-labeled product exists.
• Never combine with nitrate-containing therapies — this is a hard, well-documented contraindication.