Tadalafil and Raltegravir: Can They Be Taken Together?

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What is tadalafil and raltegravir used for?

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed to treat erectile dysfunction in men [3][4]. It works by relaxing blood vessels in the penis, allowing increased blood flow when you are sexually aroused. Tadalafil is available as an on-demand tablet (10 mg or 20 mg, taken at least 30 minutes before sex, with effects lasting up to 36 hours) or as a daily low-dose tablet (2.5 mg or 5 mg) [4]. It requires sexual stimulation to work and does not increase sexual desire on its own.

Raltegravir is an antiretroviral medicine used to treat HIV infection [12]. It belongs to a class called integrase strand transfer inhibitors (INSTIs), which work by blocking an enzyme that HIV needs to multiply inside your cells. Raltegravir is typically taken twice daily as part of combination antiretroviral therapy (ART) to keep the virus under control and maintain your immune system. It does not cure HIV but helps people living with HIV stay healthy and reduce the risk of passing the virus to others.

Many men living with HIV experience erectile dysfunction, which can have physical causes (such as changes in blood vessels or hormone levels) or psychological causes (including anxiety or depression). Effective HIV treatment and good overall health can improve ED, and prescription ED medicines like tadalafil may help when needed [1][2].

Do tadalafil and raltegravir interact with each other?

No major interaction between tadalafil and raltegravir is commonly reported in clinical practice or prescribing guidance [3][4][12]. Raltegravir is not a strong inhibitor or inducer of the liver enzymes (particularly CYP3A4) that break down tadalafil, so it is unlikely to significantly raise or lower tadalafil levels in your blood. This means the two medicines can generally be taken together without needing to adjust the dose of either one.

However, it is important to remember that raltegravir is almost always prescribed alongside other antiretroviral medicines as part of combination therapy. Some of these other HIV medicines—particularly protease inhibitors boosted with ritonavir or cobicistat—are potent CYP3A4 inhibitors and can raise tadalafil levels significantly [3][4]. If you are taking a boosted protease inhibitor (such as darunavir/ritonavir or atazanavir/cobicistat), your prescriber will need to reduce the maximum dose of tadalafil to avoid side effects such as headache, flushing, or a drop in blood pressure.

During your online consultation at Cured Pharmacy, the prescriber will review every medicine you are currently taking, including all your HIV medications, to check for interactions and choose the safest dose and type of ED treatment for you. Never stop or change your HIV treatment without advice from your HIV specialist, as this could lead to drug resistance or a rise in your viral load.

Why your full HIV regimen matters

Because HIV treatment involves multiple medicines working together, it is essential to declare your entire antiretroviral regimen during your ED consultation. Even if raltegravir itself does not interact with tadalafil, a boosting agent or another drug in your combination may do so. Your prescriber will check the British National Formulary and the Summary of Product Characteristics for each medicine to ensure the combination is safe and effective [3][4][12].

When to get urgent help

• Erection lasting more than four hours (priapism) – go to A&E immediately
• Sudden loss of vision in one or both eyes – seek urgent medical attention
• Sudden decrease or loss of hearing – contact your GP or call 111 the same day
• Chest pain during or after sex – stop activity and seek medical help; do not take nitrates if you have used tadalafil in the past 48 hours
• Severe dizziness, fainting, or very low blood pressure – call 999 or go to A&E

Call 999 or go to A&E in an emergency, or contact NHS 111 for urgent advice.

What does your prescriber check before prescribing tadalafil and raltegravir together?

When you request tadalafil through Cured Pharmacy, a UK-registered prescriber will review your medical history and current medicines to ensure it is safe for you. They will ask about your HIV treatment (including the names and doses of all antiretrovirals), your viral load and CD4 count if known, and any other health conditions such as high blood pressure, heart disease, or diabetes [2][4].

The prescriber will check whether you are taking any medicines that are contraindicated with tadalafil. You must not take tadalafil if you use nitrates (such as GTN spray or isosorbide mononitrate for angina), nicorandil, riociguat, or recreational drugs called 'poppers' (amyl or alkyl nitrites), because the combination can cause a dangerous fall in blood pressure [3][4]. You should also not take tadalafil alongside another PDE5 inhibitor such as sildenafil or vardenafil.

If you take medicines for high blood pressure or an alpha-blocker for prostate symptoms (such as tamsulosin or doxazosin), the prescriber will ensure you are stable on that treatment and may start you on a lower dose of tadalafil to reduce the risk of dizziness or fainting [3][4]. They will also check that sexual activity is safe for your heart, as ED treatment is not suitable for men with severe heart failure, recent heart attack or stroke, or very low blood pressure [2][4].

How to take tadalafil safely if you are on raltegravir

If your prescriber approves tadalafil, follow the dosing instructions on your prescription carefully. For on-demand tadalafil, take one 10 mg or 20 mg tablet at least 30 minutes before you plan to have sex; the effect can last up to 36 hours, so you do not need to take it every day [4]. For daily tadalafil, take one 2.5 mg or 5 mg tablet at the same time each day, whether or not you plan to have sex. Do not take more than one dose in 24 hours.

You can take tadalafil with or without food, but be aware that a large or high-fat meal may delay how quickly it works. Avoid drinking grapefruit juice, as it can raise tadalafil levels in your blood and increase the risk of side effects [4]. Heavy alcohol can make erectile dysfunction worse and add to the blood-pressure-lowering effect of tadalafil, so limit your intake.

Continue taking your raltegravir and other HIV medicines exactly as prescribed by your HIV specialist. Do not skip doses or stop treatment, as this can lead to drug resistance and a rise in your viral load. If you experience any new symptoms or side effects after starting tadalafil—such as severe headache, dizziness, chest pain, or vision changes—contact your GP or pharmacist for advice. Store both medicines in a cool, dry place out of reach of children.

What if you take other HIV medicines alongside raltegravir?

If your HIV regimen includes a boosted protease inhibitor (such as ritonavir or cobicistat), your prescriber may reduce the maximum dose of tadalafil or recommend a longer gap between doses to avoid a build-up of the medicine in your system [3][4]. Always declare every medicine you take, including over-the-counter products and supplements, during your consultation so the prescriber can give you the safest advice.

At a glance

Are there side effects when taking tadalafil and raltegravir?

Tadalafil and raltegravir each have their own side effects, but taking them together does not usually cause new or worse problems. Common side effects of tadalafil include headache, indigestion, back pain, muscle aches, flushing, and a blocked or runny nose [3][4]. These are usually mild and go away on their own. Raltegravir can cause headache, nausea, diarrhoea, and tiredness, though many people tolerate it well [12].

Rarely, tadalafil can cause more serious side effects. Seek urgent medical help if you develop an erection lasting more than four hours (priapism), sudden loss of vision in one or both eyes, or sudden decrease or loss of hearing [3][4]. If you experience chest pain during sex, stop and seek medical advice; do not take nitrate medicines (such as GTN spray) if you have used tadalafil in the past 48 hours, as this can cause a dangerous drop in blood pressure.

If you notice any new symptoms after starting tadalafil, or if your HIV treatment side effects seem to worsen, speak to your pharmacist, GP, or HIV specialist. They can help you work out whether the symptom is related to tadalafil, your antiretroviral therapy, or another cause, and advise on the best course of action.

Other ED treatment options if you are taking raltegravir

If tadalafil is not suitable for you, or if you would prefer a different option, there are several other licensed ED treatments available in the UK. Sildenafil (generic Viagra) is taken about one hour before sex and lasts for around four to six hours [3]. Vardenafil (generic Levitra) works in about 25 to 60 minutes, and avanafil (Spedra) can work in as little as 15 to 30 minutes [5][6]. All of these are PDE5 inhibitors and have similar interactions and precautions to tadalafil.

If you are taking a boosted protease inhibitor, your prescriber will check the Summary of Product Characteristics for each PDE5 inhibitor, as some (such as vardenafil and avanafil) are contraindicated or require significant dose reductions with potent CYP3A4 inhibitors [5][6]. Sildenafil may be used at a lower starting dose, and tadalafil may be used with a reduced maximum dose [3][4].

For men who cannot use tablets, other options include Vitaros (alprostadil cream applied to the tip of the penis) or Caverject (alprostadil injection into the penis), both of which are prescription-only [7]. Eroxon is a topical gel medical device that can be bought without a prescription. Your GP or a specialist can discuss vacuum erection devices or, in some cases, referral for further investigation or psychological support [1][2]. At Cured Pharmacy, our prescribers will help you find the most suitable treatment based on your individual circumstances.

When to see your GP about erectile dysfunction

If you are experiencing erectile dysfunction for the first time, it is a good idea to see your GP for a check-up. ED can be an early warning sign of cardiovascular disease or diabetes, and your doctor can arrange blood tests and a health review [1][2]. They can also discuss any psychological factors, such as stress or relationship issues, and refer you for specialist support if needed. Treating the underlying cause can often improve ED alongside any medication.

In summary

• No major interaction between tadalafil and raltegravir is commonly reported, so they can usually be taken together safely.
• Your prescriber will review your full HIV regimen, as some boosted protease inhibitors require a reduced tadalafil dose.
• Never take tadalafil with nitrates, nicorandil, riociguat, poppers, or another PDE5 inhibitor.
• Continue your HIV treatment exactly as prescribed; do not stop or change it without specialist advice.
• Seek urgent help if you have an erection lasting over four hours, sudden vision or hearing loss, or chest pain during sex.

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