Why is stacking two ED pills a problem?
Because they are two versions of the same drug action. Sildenafil, tadalafil, vardenafil and avanafil all block PDE5, the enzyme that breaks down the chemical signal keeping penile blood vessels relaxed, and all of them relax blood vessels throughout the body to a small degree. That is why each one carries warnings about low blood pressure, especially alongside alpha-blockers, other blood pressure medicines or heavy drinking.
Doubling up doubles down on that effect. The tadalafil label states that the safety and efficacy of combining it with other PDE5 inhibitors or other ED treatments has not been studied, and tells patients not to take it with other PDE5 inhibitors.
Timing makes the overlap hard to avoid. Tadalafil has a half-life of about 17.5 hours, so a dose from yesterday is still active today. Spacing the two pills a day apart does not keep them from overlapping.
Does a second pill make erections stronger?
There is no evidence that it does. Both drugs work the same way and both need sexual stimulation to have any effect, as the sildenafil label explains. If one adequately dosed, correctly taken pill is not working, adding a second drug from the same family does not address the reason it failed. More often the cause is how the pill is being taken, a dose that is too low, or a problem the pill cannot reach, such as advanced blood vessel disease or low testosterone.
What does a provider change instead?
A provider works through the reasons one pill is falling short, in roughly this order:
| Step | What gets checked or changed |
|---|---|
| How you take it | Sildenafil works more slowly after a heavy, high-fat meal; both need arousal to work |
| Dose | Adjusted within the label range for your health and other medicines |
| Which medicine | Switching between sildenafil and tadalafil suits some men better |
| Schedule | Daily low-dose tadalafil instead of on-demand dosing |
| Hormones | The AUA guideline says these pills may work better when low testosterone is treated |
| Treatment type | Injections such as Trimix when pills are not enough |
Our pages on ED pills that stop working, sildenafil versus tadalafil and daily versus as-needed tadalafil go into each step. When pills run out of road, Trimix injections are the usual next option.
What if you have already taken both?
Watch for signs that your blood pressure has dropped too far, such as dizziness or lightheadedness. Sit or lie down if you feel lightheaded, avoid alcohol for the rest of the day, and do not take any nitrate medicine or use poppers. Mention it to your provider so the plan can be reviewed.
Emergency: Fainting, chest pain, or an erection that lasts four hours or more needs emergency care. Call 911 or go to the nearest emergency department, and tell the staff exactly which pills you took and when. Never take nitroglycerin for chest pain after an ED pill unless an emergency team is directing your care.
Is it different with Trimix and a pill?
It needs even more care, because an injection and a pill together raise the risk of an erection that will not go down. Memorial Sloan Kettering’s penile injection therapy guide, for example, tells its patients not to take sildenafil within 18 hours of an injection and not to inject within 72 hours of a 10 or 20 mg tadalafil dose. Your own provider’s instructions take priority, and our answer on using Trimix with Viagra covers it in more depth.
How Ultimate Male adjusts an ED plan that is not working
At our San Gabriel and Downey clinics, a provider reviews how you have been taking your medicine, your other medicines and your labs before changing anything. The fix is often simpler than a second pill, and when it is not, there are other treatment types with their own evidence behind them.
Read more about ED medications at Ultimate Male, or call 626-319-5261 for a free 10-minute call.
