Can You Take Viagra With Finasteride or Propecia?
Viagra and finasteride are not known to interact and can usually be taken together, but finasteride's own effect on erections is the real reason this question comes up.
Viagra can generally be taken together with finasteride (sold as Propecia for hair loss and Proscar for prostate enlargement), and the two are not listed as interacting. That is the short answer most men are looking for. The longer answer is worth reading, because finasteride has a complicated relationship with erectile function itself — and that, rather than any direct drug clash, is the real reason this question comes up so often.
Can you take Viagra with finasteride or Propecia?
According to standard drug-interaction references, there are no known interactions between Viagra (sildenafil) and finasteride. The two medicines work on completely different systems: Viagra is a PDE5 inhibitor that supports blood flow into the penis during arousal, while finasteride is a 5-alpha-reductase inhibitor that lowers the hormone DHT to slow hair loss or shrink an enlarged prostate. Because they act through separate pathways, taking them at the same time is not considered a contraindication, and many men use both without trouble.
That said, "no known interaction" is not the same as a personal green light. Absence of a documented clash does not account for your other medications or health conditions, so a quick check with a doctor or pharmacist remains sensible before combining them.
| Medication | Drug class | Main use | How it acts |
|---|---|---|---|
| Viagra (sildenafil) | PDE5 inhibitor | Erectile dysfunction | Increases blood flow to the penis during arousal |
| Finasteride (Propecia) | 5-alpha-reductase inhibitor | Hair loss | Lowers DHT to slow hair loss |
| Finasteride (Proscar) | 5-alpha-reductase inhibitor | Enlarged prostate (BPH) | Lowers DHT to shrink the prostate |
Why does finasteride get linked to erectile dysfunction?
The confusion comes from finasteride's own side-effect profile. A minority of men report reduced libido, difficulty getting an erection, or lower ejaculate volume while taking it, because lowering DHT can affect sexual function in some users. For most men these effects are mild and reverse when the drug is stopped, but a small number describe symptoms that persist — sometimes called post-finasteride syndrome. So a man may end up taking Viagra precisely because finasteride seems to have dented his erections, which is a different scenario from the two drugs interacting with each other.
If you suspect finasteride is contributing to your ED, that is a conversation to have with the prescribing doctor rather than something to self-manage. They can weigh the benefit you are getting against the sexual side effects and decide whether to continue, adjust, or stop it.
It is also worth separating cause from coincidence. Many men start finasteride in their thirties and forties — the same years when other risk factors for ED, such as rising blood pressure, weight gain or stress, begin to appear. So an erection problem that emerges during finasteride treatment is not automatically the drug's fault. A doctor can help untangle whether the finasteride, an unrelated cause, or a combination is responsible, which matters because the fix is different in each case.
What about topical hair-loss treatments?
Finasteride is increasingly used as a topical solution rather than a tablet, often combined with minoxidil. The same logic applies: there is no recognised interaction with sildenafil, but topical formulations are still absorbed to a degree, so they should be declared to whoever prescribes your ED medication. Treat every product you use — oral, topical or supplement — as relevant information for your clinician.
Using both safely
If you have been cleared to take Viagra and finasteride together, the usual sildenafil precautions still apply in full. The combination does not change the firm rules that govern Viagra on its own.
- Never take Viagra with nitrate heart medicines — see the wider list of medications you should not mix with sildenafil.
- Tell your doctor about every prescription, including blood thinners — the same caution applies to combinations such as Xarelto with Viagra or Cialis.
- If you have heart disease or take blood-pressure medication, read taking Viagra with a heart condition before starting.
- Use the lowest effective sildenafil dose and no more than once a day.
Frequently asked questions
- Is it safe to take Viagra and Propecia on the same day?
- For most men, yes — there is no known interaction between sildenafil and finasteride, and timing them together is not a problem. A pharmacist can confirm it is fine given your other medicines.
- Will finasteride stop Viagra from working?
- No. Finasteride does not block sildenafil's mechanism. If Viagra seems less effective, the cause is more likely the underlying ED or finasteride's own effect on libido than a clash between the two.
- Can finasteride cause the erectile dysfunction I am treating?
- In a minority of men it can reduce desire or erections. If symptoms began after starting finasteride, raise it with your prescriber rather than simply adding Viagra on top.
For more on Viagra safety, interactions and getting a prescription, return to our erectile dysfunction and Viagra hub.