Vardenafil and Liothyronine: Can You Take Them Together?

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Key takeaways

• No major direct interaction between vardenafil and liothyronine is commonly reported
• Always declare all medicines including thyroid treatment during your consultation
• Thyroid disorders can contribute to ED; treating them may improve symptoms
• Never take vardenafil with nitrates, nicorandil, riociguat, or poppers
• Seek urgent help for chest pain, erection over 4 hours, or sudden vision loss

What Is Vardenafil and How Does It Work?

Vardenafil is a prescription medicine used to treat erectile dysfunction (ED) in men [5]. It belongs to a group of medicines called PDE5 inhibitors, which also includes sildenafil (Viagra) and tadalafil (Cialis). Vardenafil works by relaxing the blood vessels in the penis, allowing more blood to flow in when you are sexually aroused [5]. This helps you get and keep an erection suitable for sexual activity.

Vardenafil is available in 5 mg, 10 mg, and 20 mg tablets and is usually taken about 25 to 60 minutes before sex [5]. The effect can last for several hours, but you should only take it once in any 24-hour period. Vardenafil does not work without sexual stimulation—it simply makes it easier for your body to respond naturally. At Cured Pharmacy, vardenafil is available on prescription after an online consultation with a UK-registered prescriber.

What Is Liothyronine and Why Is It Prescribed?

Liothyronine is a synthetic form of the thyroid hormone triiodothyronine (T3). It is prescribed to treat an underactive thyroid gland (hypothyroidism), a condition where your thyroid does not produce enough hormones to regulate your metabolism. Some people take liothyronine on its own, while others take it alongside levothyroxine (T4), the more commonly prescribed thyroid hormone replacement.

Thyroid hormones play a vital role in many body functions, including heart rate, body temperature, energy levels, and mood. When thyroid levels are too low, you may feel tired, gain weight, feel cold, or experience low mood. Liothyronine helps restore normal thyroid hormone levels and can improve these symptoms. It is important to take liothyronine exactly as prescribed and to have regular blood tests to monitor your thyroid function.

Can Thyroid Problems Cause Erectile Dysfunction?

Yes, thyroid disorders—both underactive (hypothyroidism) and overactive (hyperthyroidism)—can contribute to erectile dysfunction [1]. Low thyroid hormone levels can reduce libido, cause fatigue, and affect the blood flow and nerve signals needed for an erection. Treating the underlying thyroid condition with medicines such as liothyronine or levothyroxine often improves ED symptoms, though some men may still benefit from additional ED treatment such as vardenafil.

Vardenafil and Liothyronine: Is There an Interaction?

No major direct interaction between vardenafil and liothyronine is commonly reported in the medical literature or prescribing databases. This means that taking vardenafil alongside liothyronine does not usually cause the levels of either medicine to rise or fall in a clinically significant way, and the two medicines do not typically interfere with each other's mechanism of action.

However, it is still essential to declare all your current medicines—including liothyronine—when you request vardenafil. Your prescriber will review your full medication list, medical history, and any other conditions (such as heart disease or high blood pressure) to ensure vardenafil is safe and appropriate for you. Even when no direct interaction exists, your overall health picture matters, and thyroid disorders can sometimes be associated with other conditions that do affect the safety of ED medicines.

Why Your Prescriber Still Needs to Know About Liothyronine

Although vardenafil and liothyronine do not interact directly, your prescriber needs to know you are taking thyroid hormone replacement because thyroid disorders can affect your cardiovascular system. For example, if your thyroid hormone levels are not well controlled, you may have an increased heart rate or irregular heartbeat, which could influence whether vardenafil is suitable for you. Your prescriber will also check for any other medicines you take and any heart, blood pressure, or liver conditions before approving vardenafil [5].

What Your Prescriber Checks Before Approving Vardenafil

When you request vardenafil through Cured Pharmacy, a UK-registered prescriber will review your online consultation to ensure the medicine is safe for you. They will check your current medicines, including liothyronine, to identify any potential interactions or contraindications. Vardenafil must never be taken with nitrates (such as GTN spray or isosorbide mononitrate), nicorandil, riociguat, or recreational drugs called 'poppers', because this combination can cause a dangerous drop in blood pressure [5].

Your prescriber will also ask about any heart conditions, recent stroke or heart attack, very low blood pressure, liver or kidney problems, and whether you take alpha-blockers (such as tamsulosin or doxazosin) or medicines that affect liver enzymes (such as ritonavir, ketoconazole, or clarithromycin) [5]. If you take an alpha-blocker, you may need to start on a lower dose of vardenafil and be stable on the alpha-blocker first. The prescriber will also consider your thyroid status and whether your thyroid hormone levels are well controlled, as this can affect your overall cardiovascular health.

Practical Advice for Taking Vardenafil with Liothyronine

If your prescriber approves vardenafil, you can usually take it at any time of day that suits you, about 25 to 60 minutes before planned sexual activity [5]. Liothyronine is typically taken once or twice daily, often in the morning and sometimes in the afternoon, depending on your doctor's instructions. There is no need to time vardenafil around your liothyronine dose, as the two medicines do not interfere with each other.

Continue taking your liothyronine exactly as prescribed by your GP or endocrinologist, and attend regular blood tests to monitor your thyroid function. Do not stop or change your thyroid medicine without medical advice. If you notice any new symptoms—such as chest pain, dizziness, palpitations, or an erection lasting more than four hours—seek medical help immediately. Heavy alcohol can worsen erectile dysfunction and add to the blood-pressure-lowering effect of vardenafil, so it is best to limit alcohol when planning to use ED treatment [1][5].

Can I Take Vardenafil with Other Thyroid Medicines?

Levothyroxine (T4) is the most commonly prescribed thyroid hormone replacement, and no major interaction between vardenafil and levothyroxine is commonly reported either. The same principles apply: declare all your medicines during the consultation, and your prescriber will check your overall health and medication list. If you take a combination of liothyronine and levothyroxine, or any other thyroid medicine, make sure to list them all when you request vardenafil.

When to See Your GP and Warning Signs to Watch For

If you have new or worsening erectile dysfunction, it is important to see your GP for a full assessment [1][2]. ED can be an early warning sign of underlying conditions such as heart disease, diabetes, or high blood pressure, and treating these conditions may improve your erections. Your GP can also check your thyroid function and adjust your liothyronine dose if needed, as poorly controlled thyroid levels can contribute to ED.

While taking vardenafil, seek urgent medical help if you experience chest pain during sex, an erection lasting more than four hours (priapism), sudden loss of vision or hearing, or severe dizziness or fainting [5]. These are rare but serious side effects that require immediate attention. If you develop new symptoms after starting vardenafil, or if your thyroid symptoms change (such as a racing heart, tremor, or feeling unwell), contact your GP or pharmacist for advice. Never stop taking your prescribed thyroid medicine without speaking to your doctor first.

When to get urgent help

• Chest pain or discomfort during or after sex
• An erection lasting more than 4 hours (priapism)
• Sudden loss of vision in one or both eyes
• Sudden decrease or loss of hearing, possibly with ringing in the ears or dizziness
• Severe dizziness, fainting, or feeling like you might pass out

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

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