Can Viagra and Cialis cause heartburn and indigestion? Yes. Indigestion is a common side effect of both sildenafil (Viagra) and tadalafil (Cialis), and reflux an uncommon one (EMA — Viagra; EMA — Cialis). healthdirect lists indigestion or reflux with headache, flushing and nasal congestion as the common side effects of erectile dysfunction medicines: "Usually, these side effects are mild and temporary" (healthdirect — ED medicines). Heart attack pain can feel like indigestion, so if you are not sure, call triple zero (000) (healthdirect — Indigestion).
How common is indigestion with Viagra and Cialis?
From about 1 man in 25 to 1 in 6, depending on the medicine and dose, against 1 or 2 in 100 on placebo:
| Medicine and dose | Indigestion on the medicine | On placebo |
|---|---|---|
| Viagra, taken as needed (flexible-dose trials) | 7% | 2% |
| Viagra 100 mg (fixed-dose trials) | 17% | not given |
| Cialis 10 or 20 mg (12 weeks) | 10.4% | 1.6% |
| Cialis 2.5 or 5 mg once a day (12 weeks) | 3.9% | 1.3% |
Sources: Viagra PI (Australia) and Cialis PI (Australia), section 4.8.
Both Australian leaflets name heartburn as well as indigestion among the less serious side effects (Viagra CMI; Cialis CMI). The vardenafil label lists indigestion as common too: how can I reduce Levitra's side effects?
Why do ED medicines cause heartburn?
The labels do not say, but small studies point to the valve at the top of the stomach: "a ring of muscle at the lower end of your oesophagus stops stomach acid from escaping" (healthdirect — Heartburn). In six healthy men, 50 mg of sildenafil lowered the pressure of that muscle (Eherer et al., 2002). But in eight volunteers whose reflux was measured for two hours, sildenafil "did not alter the reflux" (Kim et al., 2006). Neither tested tadalafil.
Does a higher dose make it worse?
Yes. On Viagra, indigestion was "more common at 100 mg than at lower doses" (Viagra PI), and 200 mg brought no better effect, only more side effects (EMA — Viagra). Tadalafil's most common side effects, indigestion among them, "increase with increasing dose" (EMA — Cialis). A lower dose is for the doctor who prescribes it to decide: Viagra's usual 50 mg may be "decreased to 25 mg" (Viagra PI), and the daily 5 mg Cialis tablet can be lowered to 2.5 mg (EMA — Cialis overview). One dose a day is the limit: is it safe to take more than one Viagra?
Does food make it better or worse?
Food does not prevent it, and a heavy meal can work against you twice: "You may find VIAGRA takes longer to work if you take it with a heavy meal" (Viagra CMI), and large meals and fatty or spicy foods are also common heartburn triggers, with coffee, fizzy drinks, citrus fruits, alcohol, chocolate and peppermint (healthdirect — Heartburn). Food does not change how tadalafil is absorbed (EMA — Cialis). More on timing: is it best to take Viagra on an empty stomach or after eating? and does grapefruit juice affect Viagra?
Can you take an antacid or reflux medicine with Viagra or Cialis?
An antacid, yes. "Single doses of antacid (magnesium hydroxide/aluminium hydroxide) did not affect the bioavailability of VIAGRA" (Viagra PI). With tadalafil, an antacid slowed absorption "without altering exposure", and nizatidine, an H2 antagonist that lowers stomach acid, "had no significant effect" (Cialis PI).
One acid medicine is on the Viagra leaflet's interaction list: "cimetidine, a medicine used to treat ulcers" (Viagra CMI). In volunteers it raised sildenafil levels by 56% (Viagra PI). Proton pump inhibitors (PPIs) are not named on either label. Before taking any heartburn medicine, tell the pharmacist or doctor that you use sildenafil or tadalafil (healthdirect — Heartburn).
When is it not heartburn?
When you cannot be sure: do not assume chest pain after an ED tablet is heartburn. "If you are unsure if your symptoms are caused by indigestion or a heart attack, you should call triple zero (000)" (healthdirect — Indigestion). For pain during or after sex, the Cialis leaflet says to "stop what you are doing, sit up and sit forward. Call an ambulance if the pain does not resolve. Do not use nitrates" (Cialis CMI): nitrates, the medicines for angina, are never taken with an ED medicine. A fast heartbeat and heart palpitations are uncommon side effects on both labels (EMA — Viagra; EMA — Cialis).
When should you see a doctor about heartburn?
When it keeps coming back: see your doctor "If you have heartburn regularly, like 2 times a week or more", if over-the-counter medicines do not help, or for weight loss, trouble swallowing, or vomiting, especially with blood (healthdirect — Heartburn). Tell the doctor who prescribes your ED medicine if you have a stomach ulcer: there is no safety information on sildenafil in active peptic ulcers, so it "should be administered with caution" (Viagra PI).
The short answer
Yes, and more so at higher doses; it is usually mild and short-lived. An antacid does not change how much sildenafil or tadalafil reaches the blood; cimetidine is the acid medicine to mention to your doctor. If it keeps happening, a lower dose or a different medicine is your doctor's call. Every other side effect is in our guide to side effects of ED medicines.
