Famotidine, a histamine-2 receptor antagonist used to treat acid-related conditions such as gastro-oesophageal reflux disease and peptic ulcers, is generally well-tolerated with a favourable safety profile. Concerns occasionally arise about whether famotidine might cause erectile dysfunction, particularly given historical associations between older H2 blockers like cimetidine and sexual side effects. However, current evidence does not support a causal link between famotidine and erectile dysfunction. This article examines the pharmacology of famotidine, reviews the evidence regarding sexual side effects, and provides guidance on managing erectile difficulties whilst taking this medication.

What Is Pepcid and How Does It Work?

Famotidine (brand name Pepcid, though this brand is not commonly marketed in the UK) is a medication belonging to the class of drugs known as histamine-2 receptor antagonists (H2 blockers). In the UK, famotidine is available on prescription for the treatment of various acid-related gastrointestinal conditions. It is primarily used to manage conditions such as gastro-oesophageal reflux disease (GORD), peptic ulcers, and dyspepsia.

Famotidine works by selectively blocking histamine H2 receptors located on the parietal cells of the gastric mucosa. When histamine binds to these receptors under normal circumstances, it stimulates the production of gastric acid. By competitively inhibiting this binding, famotidine reduces both the volume and acidity of gastric secretions. This mechanism provides symptomatic relief from heartburn, reduces the risk of ulcer formation, and promotes healing of existing ulcers.

The medication is typically administered orally, with standard doses ranging from 20 mg to 40 mg once or twice daily, depending on the condition being treated. Famotidine has a relatively rapid onset of action, usually within one hour, and its effects can last for up to 12 hours. It is generally well-tolerated, with a favourable safety profile compared to older H2 blockers.

Common side effects include headache, dizziness, constipation, and diarrhoea, though these are usually mild and transient. Serious adverse effects are very rare but may include cardiac arrhythmias (primarily with intravenous administration or in patients with significant comorbidities) or confusion in elderly patients. Dose adjustments are necessary in patients with renal impairment, particularly when creatinine clearance is below 30 mL/min, due to reduced drug clearance.

Can Pepcid Cause Erectile Dysfunction?

The evidence that famotidine causes erectile dysfunction is limited. Historically, some H2 receptor antagonists—particularly cimetidine—have been associated with sexual dysfunction, including erectile difficulties, reduced libido, and gynaecomastia. This is thought to occur because cimetidine has anti-androgenic properties, binding to androgen receptors and potentially affecting testosterone metabolism.

However, famotidine has a different pharmacological profile and does not exhibit the same anti-androgenic effects as cimetidine. The current evidence does not demonstrate that famotidine causes erectile dysfunction. A review of the available literature and post-marketing surveillance data suggests that sexual dysfunction is not a commonly reported adverse effect of famotidine therapy. Importantly, erectile dysfunction is not listed as a recognised side effect in the UK Summary of Product Characteristics (SmPC) for famotidine.

That said, isolated case reports have occasionally suggested a possible association, though these are anecdotal and do not establish causation. It is important to recognise that erectile dysfunction is a multifactorial condition influenced by numerous factors including age, cardiovascular health, diabetes, psychological stress, and concurrent medications. Patients taking famotidine who experience erectile difficulties may have underlying conditions or be taking other medications that are more likely contributors.

There is no official link established by regulatory authorities such as the MHRA or EMA between famotidine and erectile dysfunction. Nevertheless, if a temporal relationship is observed—where erectile problems begin shortly after starting famotidine—it is reasonable to discuss this with a healthcare professional to explore alternative explanations and management options. Under medical supervision, a trial of stopping and restarting the medication might help determine if there is a causal relationship in individual cases.

Other Medications That May Affect Erectile Function

Erectile dysfunction can be influenced by a wide range of medications, and it is essential for both patients and clinicians to be aware of these potential associations. Antihypertensive medications are among the most commonly implicated drugs. Beta-blockers (such as propranolol and atenolol) and thiazide diuretics (such as bendroflumethiazide) have been associated with erectile difficulties, though newer agents like ACE inhibitors and angiotensin receptor blockers generally have a lower risk. Some beta-blockers, such as nebivolol, may have fewer sexual side effects than others in the same class.

Antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs) such as sertraline, fluoxetine, and citalopram, are well-recognised causes of sexual dysfunction, including delayed ejaculation, reduced libido, and erectile problems. These effects are thought to result from increased serotonin levels affecting dopamine and nitric oxide pathways involved in sexual arousal and function.

Antipsychotic medications, including both typical agents (such as haloperidol) and atypical antipsychotics (such as risperidone), can cause erectile dysfunction through their effects on prolactin levels and dopamine pathways. Elevated prolactin can suppress testosterone production and directly impair erectile function.

Other medication classes that may affect erectile function include:

• Antiandrogens and hormonal therapies used in prostate cancer treatment (such as bicalutamide and goserelin)

• Finasteride and dutasteride, used for benign prostatic hyperplasia and male pattern baldness

• Opioid analgesics, which can reduce testosterone levels with chronic use

• H2 receptor antagonists, particularly cimetidine, which has anti-androgenic properties

• Spironolactone, which has anti-androgenic effects

• Some antiepileptics, such as carbamazepine

• Benzodiazepines and alcohol, which may affect sexual function

If erectile dysfunction develops after starting a new medication, patients should consult their GP or prescribing clinician rather than discontinuing treatment independently. In many cases, alternative medications with a lower risk profile can be considered, or additional treatments for erectile dysfunction may be appropriate.

What to Do If You Experience Erectile Dysfunction on Pepcid

If you develop erectile dysfunction whilst taking famotidine, it is important to approach the situation systematically and seek appropriate medical advice. Do not stop taking your medication without first consulting your GP or pharmacist, as abrupt discontinuation may lead to a recurrence of acid-related symptoms.

The first step is to arrange an appointment with your GP to discuss your concerns. Your doctor will take a comprehensive history to establish the timeline of your symptoms and identify any other potential contributing factors. This assessment should include:

• A review of all current medications, including over-the-counter preparations and supplements

• Evaluation of cardiovascular risk factors (hypertension, diabetes, hyperlipidaemia, smoking)

• Assessment of psychological factors such as stress, anxiety, or depression

• Consideration of lifestyle factors including alcohol consumption and physical activity levels

Your GP may perform or arrange relevant investigations in line with NICE guidance, which may include blood tests to assess morning testosterone levels (taken between 8-11am and repeated if low), glucose, lipid profile, and thyroid function. If you have low libido or breast tenderness, prolactin levels may also be checked. These tests help identify underlying conditions that may be contributing to erectile dysfunction.

If your doctor suspects that famotidine may be contributing to your symptoms, they may consider switching to an alternative medication. Proton pump inhibitors (PPIs) such as omeprazole or lansoprazole are effective alternatives for acid suppression and are not consistently associated with erectile dysfunction. Alternatively, if your symptoms are mild and intermittent, lifestyle modifications and antacids may be sufficient.

Treatment options for erectile dysfunction itself include phosphodiesterase-5 (PDE5) inhibitors such as sildenafil. Generic sildenafil is usually available on NHS prescription, while other PDE5 inhibitors may be subject to specific prescribing criteria. Your GP can discuss whether these treatments are appropriate for you, taking into account any contraindications. PDE5 inhibitors must not be used with nitrates or riociguat due to dangerous blood pressure drops, and caution is needed with alpha-blockers.

Your GP may consider referral to a specialist if you have confirmed hypogonadism (low testosterone), penile deformity, or erectile dysfunction that doesn't respond to initial treatment. If you experience an erection lasting more than 4 hours or chest pain after taking erectile dysfunction medication, seek urgent medical attention.

Remember that erectile dysfunction is a common condition affecting many men, particularly with increasing age, and effective treatments are available. If you suspect famotidine or any medication is causing side effects, you can report this through the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk).

Frequently Asked Questions