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What To Expect When Your Partner Takes Viagra: A Comprehensive Guide
What To Expect When Your Partner Takes Viagra: A Comprehensive Guide
Dr. Zoë Lees (PhD)
Dr. Sophie Dix (BSc, PhD)
10 October 2024 | Updated: 26 May 2026
26 May 2026


Is your sexual partner trying Viagra for the first time? You may be curious as to how they’ll feel, if it’s safe and how it may impact your intimate relationship. Here’s everything you need to know, as explained by our MedExpress experts.
Article Summary:
- Viagra (sildenafil) is a prescription treatment for erectile dysfunction (ED). Its active ingredient, sildenafil, works by relaxing blood vessels and increasing blood flow to the penis. This allows for a firmer and longer-lasting erection when sexually stimulated.
- When your partner takes Viagra for the first time, understanding how it works and what to expect can help both of you feel more prepared.
- It’s also a good idea to familiarise yourself with both the common and rare side effects of Viagra use.
What is Viagra?
Viagra is a prescription medication which is licensed to help people who experience erectile dysfunction. It contains the active ingredient sildenafil, which is a phosphodiesterase 5 (PDE5) inhibitor. PDE5 inhibitors are a type of medication that cause blood vessels to relax and widen, which increases blood flow. There are other branded PDE5 inhibitor medications available, like Cialis (tadalafil), Spedra (avanafil) and Levitra (vardenafil). However, Viagra is probably the most well known, as it's been in use since the 1990s.
How does Viagra (sildenafil) work?
In the context of erectile dysfunction, PDE5 inhibitors work by relaxing the smooth muscles located in the blood vessels of the penis. This helps to improve blood flow, and makes it easier to achieve and maintain an erection. [1] It’s important to remember that these treatments don’t cause sexual arousal or increase desire. This means your partner should only experience erections as a result of the medication if they’re sexually stimulated.
How soon does Viagra start to work?
Some people may find that the medication starts to take effect within 30 minutes, but we recommend taking it one hour before planned sexual activity. It should then stay active for roughly 6 hours, meaning it will help your partner achieve an erection during that time when sexually stimulated. [2]
What happens if Viagra doesn’t work the first time?
There are a few factors that can impact the effectiveness of Viagra for erectile dysfunction. For the best results, your partner can follow these directions:
Avoid heavy meals. Eating a large meal with Viagra can slow down how quickly it works, potentially making it less effective at treating erectile dysfunction. [3]
Limit alcohol intake. Drinking alcohol can increase the risk of erectile dysfunction, and counteract the benefits of treatments like Viagra. [4]
Don’t eat or drink grapefruit. It’s safest to avoid grapefruit juice while using sildenafil, as it can stop your body from breaking down sildenafil properly. [5] This means the medicine may stay in your body for longer than intended and can increase the risk of side effects, such as dizziness or low blood pressure. In very rare cases, it may also increase the risk of a prolonged, painful erection (priapism).
You can also support your partner with their erectile dysfunction treatment through open communication and understanding. This can help them overcome issues such as performance anxiety.
Are there any side effects of Viagra?
Yes, like all prescription medications, there is some risk of side effects. Common side effects might include headaches, nausea (feeling sick), nasal congestion (stuffy nose) and indigestion. [6]
Other potential side effects include dizziness, flushed skin or blurred vision. All of these are usually mild and wear off once the treatment is no longer active. To learn about how to manage these temporary effects, take a look at our blog here.
There are also a number of rarer, severe side effects. It’s important to look out for signs of these when your partner is taking Viagra, and contact 999 immediately if they occur. [7] They include:
Chest pain: If your partner experiences chest pain while using Viagra, seek medical attention immediately by calling 999. Your partner should not drive themselves to A&E if they are experiencing chest pains. The person you speak to at 999 will give you advice about what to do.
Allergic reaction: Signs of a serious allergic reaction (anaphylaxis) include:
- Difficulty breathing
- Struggling to swallow
- Swelling of the lips, mouth, tongue or throat
- Your skin, tongue or lips turn blue, grey or pale. (If you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet.)
- You suddenly become very confused, drowsy or dizzy
- Someone faints and cannot be woken up
Sudden vision loss: In rare cases, some people report sudden vision loss or abnormal vision. Stop taking sildenafil and call your doctor or call 111 straight away if you have a sudden decrease or loss of vision.
Drop in blood pressure: Sildenafil should never be taken by individuals taking nitrates (medication for high blood pressure) as it can cause dangerously low blood pressure. If you take alpha-blockers (like doxazosin and prazosin) for high blood pressure, be careful. Sildenafil can lower blood pressure, and combining it with alpha-blockers can make it drop too much. This can cause dizziness, lightheadedness or fainting.
Priapism: If your partner experiences a prolonged erection (lasting more than 4 hours), seek immediate medical attention by calling 999.
Viagra has been thoroughly tested in clinical trials for the treatment of erectile dysfunction. However, if your partner has any heart problems or other long‑term health conditions, it’s important that they tell their healthcare provider before using Viagra. Once they start treatment, look out for serious symptoms like chest pain, severe dizziness, breathing difficulties or a prolonged, painful erection, and call 999 or seek urgent medical help if these occur.
For more detailed information on side effects, refer to the patient information leaflet that arrives with your treatment. Be sure to follow any specific advice from your healthcare provider.
How to tell if a man is taking Viagra?
There’s no surefire way to tell if a person is taking Viagra. While improved erectile performance and certain side effects can indicate its use, the only way to know is by having an open and honest conversation.If your partner is experiencing erectile dysfunction, or has started taking Viagra, don’t take it personally. Remember that erectile dysfunction is very common, and can be caused by a number of factors. [8] It’s rarely a reflection of sexual attraction and, with the right clinical guidance and treatment, can often be managed.
How will Viagra affect my sex life?
Many couples report an improvement in their sex lives and sexual satisfaction after starting Viagra. [9] Here's what other MedExpress users have said about their experience with Viagra and other erectile dysfunction treatments:
“I was beginning to have slight erectile problems, but these are now well in the past due to taking the medication. I’m now experiencing very long lasting and powerful erections.” David, GB
“I had been unable to keep an erection whilst having intercourse with my partner so I decided to get some help. They made my erection last longer and even the length of intercourse had lasted longer.” Anon, GB
“Both myself and my wife are very satisfied… as it stipulates, don’t eat too much before taking as this does have a slight effect.” Stephen, GB
“My sex life is now back on track, thank you MedExpress.” Paul, GB
“My wife is very happy.” Nick, GB
“It's improved my love life considerably. Fantastic results.” Dave, GB
“Sildenafil is excellent. It has the right effect with no side effects, it makes sex possible again.“ John, GB
If you or your partner are ready to explore treatment, MedExpress offers a range of erectile dysfunction treatments with no in-person appointment needed. Whether that's starting with Viagra or trying Cialis for a longer-lasting option, our clinical team will find the right fit based on your individual health and needs.
References
- Dhaliwal A, Gupta M. PDE5 Inhibitor [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK549843/
- NHS. About Sildenafil (Viagra) [Internet]. nhs.uk. 2022. Available from: https://www.nhs.uk/medicines/sildenafil-viagra/about-sildenafil-viagra/
- Sildenafil Patient Information Leaflet [Internet]. Medicines.org.uk. 2022. Available from: https://www.medicines.org.uk/emc/files/pil.7141.pdf
- Li S, Song JM, Zhang K, Zhang CL. A Meta-Analysis of Erectile Dysfunction and Alcohol Consumption. Urologia Internationalis. 2021;105(11-12):969–85. https://pubmed.ncbi.nlm.nih.gov/34521090/
- Jetter A. Effects of grapefruit juice on the pharmacokinetics of sildenafil. Clinical Pharmacology & Therapeutics. 2002 Jan;71(1):21–9.
- Sildenafil 50 mg film-coated tablets - Patient Information Leaflet (PIL) - (emc) [Internet]. www.medicines.org.uk. Available from: https://www.medicines.org.uk/emc/product/7141/pil#about-medicine
- Sildenafil 50 mg film-coated tablets - Summary of Product Characteristics (SmPC) - (emc) [Internet]. www.medicines.org.uk. Available from: https://www.medicines.org.uk/emc/product/7141/smpc#gref
- Erectile dysfunction [Internet]. www.nhsinform.scot. Available from: https://www.nhsinform.scot/illnesses-and-conditions/sexual-and-reproductive/erectile-dysfunction-impotence
- Mulhall JP, Jahoda A, Aviv N, Valenzuela R, Parker M. The impact of sildenafil citrate on sexual satisfaction profiles in men with a penile prosthesis in situ. BJU International [Internet]. 2003 Dec 17;93(1):97–9. Available from: https://pubmed.ncbi.nlm.nih.gov/14678377/
Next scheduled review date: 26 May 2029

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Authors

Written by: Dr. Zoë Lees (PhD)
Dr. Zoë Lees is a medical writer at MedExpress specialising in obesity and health communication. She completed her PhD at the University of Glasgow, where she investigated adipose tissue (fat tissue) function in pregnancies complicated by pre-eclampsia and gestational diabetes. Her work focuses on translating complex clinical evidence into clear, engaging and evidence-based health information for patients and the public. At MedExpress, Zoë contributes to clinical content, educational resources and media communications across areas including weight management, GLP-1 therapies and metabolic disease. Zoë is particularly interested in improving public understanding of obesity as a chronic condition and ensuring patients have access to accurate, accessible health information grounded in current scientific evidence.

Medically reviewed by: Dr. Sophie Dix (BSc, PhD)
Dr. Sophie Dix is Head of Medical Affairs at MedExpress. A behavioural neuroscientist by training, Sophie has spent 30 years working at the intersection of medical research, pharmacology, technology and patient communication across the pharmaceutical industry, health technology and charity sectors. At MedExpress, Sophie's role is to ensure that everything the organisation does is grounded in the most current science. That means translating complex clinical evidence into accessible health information across the website, clinical pathways and media communications. It also means working with external press and broadcast media as a named expert commentator, making the science behind weight management and GLP-1 treatments understandable to a general audience. A core part of Sophie's work is building MedExpress's Real-World Evidence (RWE) programme: learning systematically from patient outcomes to understand what works in practice, not just in clinical trials. This patient-level insight feeds directly into improving patient experience and health outcomes. Sophie believes that patients make better decisions when they have access to accurate, evidence-based information. As an advocate for meaningful change in how obesity is understood, Sophie works to reduce stigma and raise awareness of the condition as an illness. This includes reframing the conversation around GLP-1s from aesthetics to public health, while highlighting the health benefits of weight loss and weight management.
Note from the experts
Remember: This blog shouldn’t be regarded as medical advice, diagnosis, or treatment. We make sure everything we publish is fact checked by clinical experts and regularly reviewed, but it may not always reflect the most recent health guidelines. Always speak to your doctor about any health concerns you have.