Podcast episode 44 (in German)
Viagra (sildenafil): the blue pill fact-checked
August 15, 2026
Viagra was a failed heart drug, became the world’s most famous pill by chance and is now resurfacing in Alzheimer’s research. The episode shows why sildenafil is more than a men’s topic.
What it is about
Sildenafil was created in Pfizer’s laboratory as a drug for angina pectoris. The heart studies were disappointing, but volunteers in Wales reported reliable erections, and Pfizer turned the program around. The episode explains the mechanism: nitric oxide leads to the formation of cGMP, which relaxes the blood vessels, and sildenafil blocks PDE5, the enzyme that breaks down cGMP. Without arousal nothing happens; the pill only amplifies a signal that is already there. Added to this are the approval for pulmonary hypertension, the use in altitude medicine, the observational data on Alzheimer’s and the erection as an early warning system for the blood vessels. At the end stands an inexpensive, prescription-only generic with one absolute contraindication: nitrates.
Key points
- Pfizer synthesized the substance in 1989 as UK-92480 for angina pectoris; FDA approval as the first erectile dysfunction pill followed on March 27, 1998.
- In the same year, 1998, the Nobel Prize in Medicine went to Furchgott, Ignarro and Murad for the discovery of nitric oxide as a signaling molecule, the mechanism behind Viagra.
- The effect begins after about 30 to 60 minutes and lasts 4 to 6 hours; a high-fat meal can delay absorption by up to 1 hour.
- Because PDE5 is also found in the pulmonary blood vessels, sildenafil has been approved under the name Revatio for pulmonary hypertension since 2005, including for children.
- In insurance data from the Cleveland Clinic from 2021, users had a 69 percent lower risk of Alzheimer’s; a 2024 analysis of more than 270,000 men found 18 percent less, and 44 percent less among the most frequent users.
- Erection problems often reveal incipient vascular disease years before the first heart symptom, because the penile arteries are narrower than the coronary arteries.
Where the data stop
The Alzheimer’s figures are observational data, not a proven cause: a Harvard analysis did not find the effect, and men who use erectile dysfunction drugs may be more active overall. Controlled trials are underway, as of August 2026. The lower cardiovascular mortality among users also comes from observational studies. At sea level, sildenafil gives healthy people no performance advantage, and in women the results are mixed.
Nitrates, that is, nitro sprays and tablets for the heart, must never be combined with sildenafil; blood pressure can drop to life-threatening levels. Anyone taking alpha blockers or with serious heart problems needs medical advice beforehand. Visual disturbances and a prolonged erection are emergencies. Counterfeit pills are one of the largest counterfeit markets in the world; the safe route is a prescription.
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Published on August 15, 2026.
The topic in the database
- The original: the world’s most famous pill – from failed heart drug to the first approved erectile dysfunction drug; today also of interest for vascular …Viagra (Sildenafil)
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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-09-26.