Can You Take Cialis With Terazosin?

In our latest submission, our pharmacist answers several questions about Cialis, including whether or not it is safe with terazosin.

4 min read Updated Jun 2026 Read by 3,054 people
Can You Take Cialis With Terazosin?
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Edmund asked

What is the highest strength of Cialis? Also, I am currently taking Terazosin for treatment of BPH, can I take Cialis?

Oct 11, 2022
The quick answer
  • Cialis and terazosin are generally not recommended together because they can both lower blood pressure, potentially causing dizziness and lightheadedness. If you need both medications, your doctor should monitor your blood pressure carefully since some studies suggest the combination may be safe and beneficial for certain patients. Alternative alpha-blocker medications like tamsulosin or silodosin are less likely to cause blood pressure drops when combined with Cialis.
A quick summary of Dr. Brian Staiger, PharmD's full answer below, condensed by AI from that answer only (not from any outside source). The pharmacist's answer is the source of record.
Medications in this answer — tap to explore

Answer

Hello and thanks for reaching out to us! I'm more than happy to answer these questions regarding Cialis (tadalafil) for you.

What Is The Highest Strength Of Cialis?

To answer your first question, Cialis is available in the following strengths:

  • 2.5mg tablet
  • 5mg tablet
  • 10mg tablet
  • 20mg tablet
  • 20mg/5mL suspension (only available as the brand name Tadliq)

As you can see, the highest available strength of Cialis is 20mg.

In regard to the FDA-approved dosing for Cialis, for erectile dysfunction, the maximum daily dose is 20mg per day if used on an intermittent, as-needed, basis, or 5mg per day if taken continually.

Can You Take Cialis With Terazosin?

Getting on to your next question, Cialis generally is not recommended to take along with terazosin, although some studies suggest that the combination may be beneficial for some people.

Terazosin is an alpha-adrenergic receptor blocker, a drug class that is generally used as a first-line option for treating BPH (benign prostatic hyperplasia). They work by blocking signaling through the alpha-adrenergic receptors in the bladder, which leads to the relaxation of the smooth muscle of the bladder and prostatic urethra.

Cialis, a PDE5 inhibitor, while most commonly used for erectile dysfunction, is also FDA-approved for the treatment of BPH, and works via a different mechanism.

Interaction Details

Although it is very common to prescribe two drugs, that work differently, for the same condition, that needs to be done cautiously here due to concerns with blood pressure dropping too low.

The concomitant administration of alpha 1-blockers, like terazosin, and PDE5 inhibitors, like Cialis, can cause mild-moderate reductions in blood pressure and symptoms of clinical concern, such as dizziness and lightheadedness.

Additionally, significant drops in blood pressure (ie, more than 30 mmHg) have been noted in some individuals as well but this significant of a drop in BP appears to be relatively uncommon.

The prescribing information for Cialis does specifically warn against using alpha-blockers at the same time:

CIALIS is not recommended in combination with alpha-blockers for the treatment of BPH because efficacy of the combination has not been adequately studied and because of the risk of blood pressure lowering. Caution is advised when CIALIS is used as a treatment for ED in men taking alpha-blockers
Cialis Prescribing Information

Now, having said this, as mentioned, there are studies that suggest the combination of an alpha-blocker and Cialis can be safe and effective. One such study concluded the following:

The combined use of PDE5 inhibitors and alpha-blockers results in additive favorable effects in men with ED [erectile dysfunction] and LUTS [lower urinary tract symptoms] suggestive of BPH compared with PDE5 inhibitor monotherapy. The alpha-blockers may enhance the efficacy of the PDE5 inhibitors, which is beneficial for the treatment of ED and LUTS.
J Sex Med . 2014 Jun;11(6):1539-45

The overall point is that you want to use drugs like Cialis and terazosin together cautiously, and be sure you and your doctor are monitoring your blood pressure, as well as the signs and symptoms of low blood pressure.

Alternatives

If you want to avoid the potential interaction between Cialis and terazosin, there are several other 'alpha blocker' drugs on the market that are less likely to lower blood pressure, even though they work on the same receptors. These drugs include:

  • Flomax (tamsulosin)
  • Rapaflo (silodosin)
  • Uroxatral (alfuzosin)

These drugs all work the same way as terazosin, but are more selective for receptors in the bladder, leading to a lower risk of blood pressure changes when compared to terazosin. Combining Cialis with one of these would generally be considered less risky than with terazosin.

There are also other drug classes entirely that are used for BPH, like finasteride, a 5-alpha reductase inhibitor. It's not uncommon to see this drug used in combination with others (in fact, it is combined with tadalafil in a single drug product, Entadfi).

Final Words

I hope you found this answer helpful and please reach back out again anytime!

References & sources
  1. Cialis Prescribing Information — Lilly
  2. A systematic review and meta-analysis on the use of phosphodiesterase 5 inhibitors alone or in combination with α-blockers for lower urinary tract symptoms due to benign prostatic hyperplasia — PubMed
  3. The efficacy of PDE5 inhibitors alone or in combination with alpha-blockers for the treatment of erectile dysfunction and lower urinary tract symptoms due to benign prostatic hyperplasia: a systematic review and meta-analysis — PubMed
  4. [Instructions for the combination of PDE5 inhibitors with alpha-blockers] — PubMed
  5. Combined tadalafil and α-blocker therapy for benign prostatic hyperplasia in patients with erectile dysfunction: a multicenter, prospective study — PubMed
  6. Combination of phosphodiesterase-5 inhibitors and alpha-blockers in patients with benign prostatic hyperplasia: treatments of lower urinary tract symptoms, erectile dysfunction, or both? — PubMed
Glossary — Terms in This Answer
PDE5 inhibitor
A medication that works by blocking an enzyme called PDE5, which helps relax blood vessels and smooth muscle in the body.
Alpha-adrenergic receptor blocker
A type of medication that blocks certain nerve signals to help relax muscles in the bladder and prostate.
Benign prostatic hyperplasia (BPH)
A non-cancerous enlargement of the prostate gland that can cause urinary symptoms.
Concomitant administration
Taking two or more medications at the same time.
Lower urinary tract symptoms (LUTS)
Problems related to urination, such as difficulty emptying the bladder or frequent urges to urinate.
Monotherapy
Treatment using a single medication rather than multiple drugs.
5-alpha reductase inhibitor
A class of medication that reduces the production of a hormone involved in prostate enlargement.
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Dr. Brian Staiger, PharmD
About the pharmacist

Dr. Brian Staiger, PharmD

Clinical Pharmacy

Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified

Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...

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