Tadalafil Side Effects: What to Expect and When to Call Your Doctor

What You Should Know About Tadalafil Side Effects

Tadalafil (brand name Cialis) is one of the most widely prescribed medications for erectile dysfunction (ED) and benign prostatic hyperplasia (BPH). Like any medication, it can cause side effects — but most are mild and go away on their own.

This guide covers the common and serious side effects of Tadalafil based on FDA labeling, who may be at higher risk, and when you should call your doctor.

What Is Tadalafil?

Tadalafil is a phosphodiesterase-5 (PDE5) inhibitor that works by relaxing blood vessels and increasing blood flow. It's FDA-approved for ED, BPH, and pulmonary arterial hypertension (PAH, under the brand name Adcirca). For a full overview, see our guide on what Tadalafil is and how it's used.

Common Side Effects of Tadalafil

The following side effects are reported in clinical trials and FDA labeling. They occur in more than 2% of patients and are usually mild to moderate:

• Headache — the most frequently reported side effect, affecting up to 15% of patients at higher doses
• Dyspepsia (indigestion) — stomach discomfort, heartburn, or acid reflux
• Back pain — typically appears 12–24 hours after taking Tadalafil and resolves within 48 hours
• Myalgia (muscle pain) — similar to back pain in timing and duration
• Nasal congestion — stuffy or runny nose
• Flushing — warmth or redness in the face, neck, or chest
• Pain in extremities — aching in arms or legs

These side effects are more common at higher doses (10 mg and 20 mg as-needed) and tend to decrease with continued use. Most people find them manageable.

Serious Side Effects

Serious side effects are rare but require immediate medical attention. Contact your doctor or go to the emergency room if you experience:

Priapism

An erection lasting more than 4 hours is a medical emergency. Priapism can permanently damage the penis if not treated promptly. If this happens, go to the ER immediately — do not wait for it to resolve on its own.

Sudden Vision Loss

Tadalafil has been associated with non-arteritic anterior ischemic optic neuropathy (NAION), a condition that causes sudden, painless vision loss in one eye. This is very rare but serious. Stop taking Tadalafil and see a doctor right away if you experience any sudden change in vision.

Sudden Hearing Loss

Some patients have reported sudden decrease or loss of hearing, sometimes with ringing in the ears (tinnitus). Stop taking Tadalafil and seek medical help immediately if this occurs.

Severe Hypotension (Dangerously Low Blood Pressure)

Tadalafil lowers blood pressure. If combined with nitrates (such as Nitroglycerin or Isosorbide Mononitrate) or certain other blood pressure medications, it can cause a severe, potentially life-threatening drop in blood pressure. Symptoms include dizziness, fainting, and lightheadedness. This is why Tadalafil is contraindicated with nitrates — see our guide on Tadalafil drug interactions.

Allergic Reactions

Rarely, Tadalafil can cause allergic reactions including rash, hives, swelling of the face or throat, and difficulty breathing. Seek emergency help if you experience these symptoms.

Chest Pain During Sexual Activity

If you experience chest pain, dizziness, or nausea during sexual activity after taking Tadalafil, stop and seek medical help. Sexual activity puts extra strain on the heart, and these symptoms could indicate a cardiovascular problem.

Side Effects in Specific Populations

Older Adults

People over 65 may experience side effects more frequently because their bodies process the medication more slowly. Doctors often start older patients on a lower dose.

People With Kidney or Liver Problems

Tadalafil is processed by the liver. Patients with moderate liver impairment should not exceed 10 mg as-needed, and those with severe liver impairment should avoid Tadalafil. For severe kidney impairment (CrCl below 30 mL/min), the maximum as-needed ED dose is 5 mg.

People on Blood Pressure Medications

If you take alpha-blockers like Tamsulosin (Flomax) or Doxazosin for BPH or high blood pressure, Tadalafil can amplify their blood-pressure-lowering effects. Your doctor will typically start with the lowest Tadalafil dose and monitor your blood pressure.

People With Heart Conditions

Patients who are medically advised against sexual activity due to cardiovascular risk should not take Tadalafil for ED. If you've had a recent heart attack, stroke, or have unstable angina, talk to your cardiologist before starting Tadalafil.

How to Manage Common Side Effects

If you experience mild side effects, these tips may help:

• Headache: Over-the-counter pain relievers like Acetaminophen (Tylenol) or Ibuprofen (Advil) can help. Stay hydrated.
• Indigestion: Take Tadalafil on a lighter stomach. Avoid spicy or fatty foods around the time you take it. An antacid may also help.
• Back pain and muscle pain: These usually resolve within 48 hours. OTC pain relievers and stretching can ease discomfort.
• Nasal congestion: A saline nasal spray or decongestant may provide relief.
• Flushing: This typically passes within a few hours. Avoid alcohol, which can make flushing worse.

If any side effect persists, worsens, or bothers you significantly, talk to your doctor. They may adjust your dose — switching from 20 mg as-needed to 5 mg daily, for example, can reduce the intensity of side effects for some patients.

When to Call Your Doctor

Call your doctor if you experience:

• An erection lasting more than 4 hours
• Sudden vision loss or changes in one or both eyes
• Sudden hearing loss or ringing in the ears
• Dizziness, fainting, or chest pain
• Severe allergic reaction (rash, swelling, difficulty breathing)
• Side effects that don't improve or get worse over time

Final Thoughts

Tadalafil is a well-studied medication with a strong safety profile when used as directed. Most side effects are mild — headache, indigestion, and back pain are the most common — and they often improve as your body adjusts. The serious side effects are rare but important to know about.

The best thing you can do is give your doctor a complete picture of your health and medications before starting Tadalafil. If you're curious about how Tadalafil works in the body, read our plain-English guide to its mechanism of action. And when you're ready to fill your prescription, Medfinder can help you find it in stock near you.