Arriving on to the market in 2003, Cialis was seen as an alternative to the breakthrough treatment Viagra, which had arrived four years previously. These treatments were ground-breaking for three reasons. Firstly, they were highly effective. Secondly, due to the fact that they are taken orally, they were convenient. Lastly, they were very well tolerated, with few drug interactions to make them unsuitable for patients.

PDE5 inhibitors such as Cialis and Viagra remain the most common, and for many the most effective, treatment for erectile dysfunction. But that is not to say that they do not have some drug interactions that need to be avoided. Taking Viagra alongside some treatments can heighten the possibility of side effects or present a serious health risk. It is therefore essential that you inform your doctor of any treatments you are currently or have recently taken, as well as any health conditions you have (contraindications) or allergies that you are aware of.

Cialis drug interactions

All medicines come with the risk of interactions occurring with others, whether they’re prescription medications or those bought over the counter. Cialis is no different. As everyone reacts differently to medications, it is not possible to predict how interactions will present precisely, but there are some well-known issues between different substances that are understood. These interactions may mean that you cannot use a combination of these treatments due to the health risks, or that there is a heightened risk of side effects when combined.

Your doctor or pharmacist should be able to inform you of what these are and you can always refer to the patient information leaflet that comes with your medication, which also lists all known side effects and their frequency, not to mention conditions that might make their use unsuitable (contraindications).

While PDE5 inhibitors are generally well tolerated and don’t interact with many other medicines, one of the few exceptions are nitrates. These are treatments for angina and heart problems. Erectile dysfunction treatment should not be taken alongside any of these medications. If someone is taking these treatments, an alternative for ED may be recommended instead.

Caverject, MUSE and Vitaros, for example, are PGE1 prostaglandins and are often effective and safe treatments for many with erectile dysfunction. Part of the reason for this is that they are administered differently than oral treatments such as tadalafil, with Caverject injected, MUSE inserted into the penis and Vitaros applied as a cream.

Amyl nitrate or ‘poppers’ should also be avoided when taking ED medications, because it can cause very serious interaction.

Avoiding adverse tadalafil interactions

Once your doctor has all the relevant information regarding other treatments you are currently taking or have recently taken, they can discuss with you any risks associated with the treatment. They will advise an alternative if they believe a treatment poses a risk.

If you are still unsure, you can always refer to the patient information leaflet that comes with your medications and lists all known interactions, contraindications and side effects.

You should avoid the following treatments while using Cialis: nitrates (including amyl nitrate or ‘poppers’); riociguat. 

The following medications may make Tadalafil unsuitable for use. This could be because they increase the risk or severity of side effects. You can discuss with your doctor whether the benefits outweigh the risks involved: alpha blockers, riociguat, 5- alpha reductase inhibitors, ketoconazole tablets, protease inhibitors, phenobarbital, phenytoin, carbamazepine, rifampicin, erythromycin , clarithromycin, itraconazole and other treatments for erectile dysfunction.

While Cialis can be taken with or without food, it is possible that large meals in particular will affect how quickly the treatment takes effect. You should avoid consumption of grapefruit juice at the same time as any PDE5 inhibitor treatment like Cialis. 

Cialis and alcohol consumption

While it is not thought to cause interactions, combining alcohol with Cialis or similar drugs such as Viagra can make the treatment less likely to work, because alcohol can make it harder to get an erection. It is therefore recommended that you avoid alcohol or, at the very least, limit its consumption to get the best from this medication.

Page last reviewed:  23/07/2020