“Little blue pill” is the widely recognized nickname for sildenafil, the active ingredient in Viagra, used to treat erectile dysfunction. It earned the name from its distinctive blue, diamond-shaped tablet. But dozens of other common medications also come as small blue pills, so identifying one correctly depends on reading the imprint code stamped on it.
Sildenafil: The Original “Little Blue Pill”
Sildenafil citrate was the first oral medication approved for erectile dysfunction, and its blue diamond shape became so iconic that “little blue pill” entered everyday language. The standard dose is 50 mg, though tablets come in strengths ranging from 25 mg to 100 mg. You take it up to four hours before sexual activity, and a single dose typically remains active in your system for four to six hours.
The medication works by blocking an enzyme that breaks down a chemical messenger responsible for relaxing smooth muscle in blood vessel walls. When that enzyme is blocked, blood vessels in the penis stay relaxed and dilated longer, allowing increased blood flow and a firmer erection in response to arousal. It doesn’t create arousal on its own. Without sexual stimulation, the pill has minimal effect.
Sildenafil is also prescribed at lower doses (10 mg and 20 mg tablets) for pulmonary arterial hypertension, a condition involving high blood pressure in the lungs. In that context it works the same way, relaxing blood vessels to reduce strain on the heart.
Generic vs. Brand-Name Pricing
The price gap between generic sildenafil and brand-name Viagra is enormous. Generic versions cost roughly 44 cents per 50 mg dose when purchased in a 30-pill quantity, while an equivalent brand-name Viagra tablet runs over $67 each. Between late 2017 and mid-2021, the list price for a common generic prescription (six tablets at 100 mg) dropped 98%, from $265 to $4. Over that same period, the equivalent Viagra prescription rose 27%, from $369 to $467. Generic sildenafil contains the same active compound and works identically.
One Critical Safety Rule
Sildenafil must never be combined with nitrate medications. Nitrates, commonly prescribed for chest pain (nitroglycerin patches, sublingual tablets, isosorbide), also relax blood vessels. Taking both at the same time can cause sudden, severe drops in blood pressure and reduced blood flow to the heart. In people with narrowed coronary arteries, this combination can trigger a dangerous cycle: falling blood pressure starves the heart of oxygen, which weakens it further, dropping blood pressure even more. The interaction can be fatal. This includes recreational “poppers” (amyl nitrate or butyl nitrate), which are chemically similar.
Before starting sildenafil, your provider will want to know about any history of heart disease, heart surgery in the past six months, irregular heartbeat, stroke, high or low blood pressure, or liver and kidney problems. People with sickle cell anemia, certain blood cancers, or structural conditions affecting the penis also need careful evaluation. Sexual activity itself places strain on the cardiovascular system, so the medication isn’t appropriate for everyone with heart-related conditions.
Other Medications That Look Like Blue Pills
If you’ve found a small blue pill and aren’t sure what it is, sildenafil is only one possibility. Dozens of medications are manufactured as blue tablets or capsules. Some of the most common include:
- Alprazolam (1 mg and 2 mg) for anxiety, appearing as blue oval or rectangular tablets with imprints like “031 R” or “B 7 0 7”
- Amphetamine/dextroamphetamine (10 mg) for ADHD, often a blue oval scored tablet imprinted “b 972/10”
- Diazepam (10 mg) for anxiety and muscle spasms, a blue round tablet imprinted “TEVA 3927”
- Cyclobenzaprine (10 mg), a muscle relaxant, appearing as a blue round pill marked “U 12”
- Sertraline (50 mg) for depression and anxiety, a blue oblong tablet
- Propranolol (20 mg), a blood pressure and heart rate medication, imprinted “PLIVA 468”
- Acetaminophen (500 mg), an over-the-counter pain reliever, sometimes manufactured as a blue oblong tablet
The only reliable way to identify an unknown pill is by its imprint code, the letters and numbers stamped into the surface. Every prescription medication sold in the U.S. has a unique imprint. You can look these up through online pill identifier tools on sites like Drugs.com or by calling a pharmacist.
How to Spot Counterfeit Pills
Because sildenafil is one of the most counterfeited medications in the world, pills purchased outside legitimate pharmacies carry real risk. Counterfeit tablets have been found to contain no active ingredient at all, the wrong dose, or dangerous contaminants. A few red flags to watch for: tablets that are cracked, crumbly, or have a bubbled coating; packaging that appears tampered with or unsealed; and any sudden change in the size, shape, or color of your medication between refills. Legitimate pharmaceutical tablets always have a uniform, factory-made appearance. If something looks off, a pharmacist can verify whether the pill matches what it should be.