Can you take Cialis and Viagra together?

Cialis (tadalafil) and Viagra (sildenafil citrate) are both PDE‑5 inhibitors used to treat erectile dysfunction (ED). They work by blocking the PDE‑5 enzyme to increase blood flow to the penis after sexual stimulation. Because both lower blood pressure, taking them together can cause dangerously low blood pressure and other complications. Always discuss with your healthcare provider before changing or combining ED treatments.

How they work

Both drugs inhibit phosphodiesterase type 5 (PDE‑5), which relaxes smooth muscle in penile blood vessels and enhances blood flow to help achieve and maintain an erection. Neither is approved for treating premature ejaculation.

Common side effects

  • Stuffy nose
  • Headache
  • Dizziness
  • Upset stomach or indigestion
  • Blurred vision
  • Nausea
  • Skin rash
  • Back pain
  • Flushing
  • Muscle aches

Serious side effects

  • Allergic reactions such as hives or facial swelling
  • Severe hypotension when combined with nitrates or alpha‑blockers
  • Heart issues in patients with unstable cardiac conditions
  • Priapism (erection lasting longer than 4 hours)
  • Sudden vision changes
  • Sudden hearing loss or ringing in the ears

If you experience any of these, seek immediate medical attention.

How to take them

Viagra is taken as needed, about one hour before activity, and lasts up to four hours. It works faster on an empty stomach.

Cialis can be taken 30 minutes before activity and may last up to 36 hours. It can be used daily at a low dose or as needed.

Drug interactions and precautions

Avoid combining these with nitrate medications (e.g., nitroglycerin) or certain alpha‑blockers, as they can cause severe blood pressure drops. Inform your provider of all prescription drugs, over‑the‑counter medicines, and supplements you use.

Other ED treatment options

  • Counseling or therapy for psychological causes
  • Other PDE‑5 inhibitors such as Levitra (vardenafil) or Stendra (avanafil)
  • Injectable alprostadil (Caverject, Edex) or urethral suppositories (MUSE)
  • Vacuum erection devices

Do not combine ED medications without medical supervision to avoid serious side effects.

Sources

  • Huang SA et al. Phosphodiesterase‑5 inhibitors in the management of erectile dysfunction. 2013.
  • Viagra (sildenafil citrate) tablet label, Pfizer, 2024.
  • Cialis (tadalafil) tablet label, Eli Lilly, 2023.