Is it safe to take beetroot powder and 33 mg of L‑tryptophan together with tadalafil (Cialis) and fluoxetine (Prozac)?

Can You Take Beetroot Powder and 33mg of Tryptophan with Tadalafil and Fluoxetine?

Yes, you can generally take beetroot powder and 33mg of L-tryptophan with tadalafil and fluoxetine, but you need to be aware of specific safety considerations, particularly regarding beetroot's potential interaction with tadalafil and the theoretical risk of serotonin syndrome when combining tryptophan with fluoxetine.

Key Safety Considerations

Beetroot Powder and Tadalafil Interaction

Beetroot powder contains high levels of dietary nitrates, which can lower blood pressure through nitric oxide pathways. When combined with tadalafil (a PDE5 inhibitor), there is a theoretical concern about additive blood pressure-lowering effects, though this differs from the absolute contraindication with pharmaceutical nitrates 1.

• Critical distinction: The FDA explicitly contraindicates tadalafil with organic nitrate medications (like nitroglycerin) due to severe hypotension risk 1
• Dietary nitrates from beetroot are metabolized differently than pharmaceutical nitrates and work through a slower, less potent mechanism
• Research shows beetroot juice lowers systolic blood pressure by approximately 5 mmHg in hypertensive patients 2
• Beetroot also acts as a competitive inhibitor of CYP3A4 (the enzyme that metabolizes tadalafil) with an IC50 of 20.97 µM, potentially increasing tadalafil blood levels 3

Practical recommendation: Monitor for symptoms of hypotension (dizziness, lightheadedness, fainting). Start with lower doses of beetroot powder and avoid taking both supplements simultaneously. Space them several hours apart if possible.

L-Tryptophan and Fluoxetine: Serotonin Syndrome Risk

The dose of 33mg tryptophan is extremely low—well below nutritional requirements (5 mg/kg daily, or ~350mg for a 70kg person) and far below supplemental doses (typically 500-5000mg). At this minimal dose, the risk of serotonin syndrome when combined with fluoxetine is negligible 4.

• Serotonin syndrome typically occurs with tryptophan doses of 70-200 mg/kg (4,900-14,000mg for a 70kg person) combined with SSRIs 4
• Your 33mg dose represents less than 1% of the typical supplemental dose
• Common side effects of higher tryptophan doses include drowsiness, tremor, nausea, and dizziness—primarily at doses >70 mg/kg 4

At 33mg, tryptophan poses minimal risk, but be aware that any increase in serotonergic activity (even theoretical) requires monitoring for serotonin syndrome symptoms: confusion, agitation, rapid heart rate, high blood pressure, dilated pupils, muscle rigidity, and hyperthermia.

Tadalafil and Fluoxetine Combination

This combination is actually studied and considered safe. Research demonstrates that tadalafil combined with fluoxetine significantly improves outcomes in premature ejaculation without major safety concerns 5, 6.

• One study showed the combination increased intravaginal ejaculatory latency time from 49.57 seconds to 336.13 seconds over 12 weeks 5
• No serious cardiovascular interactions were reported between these medications 5, 6
• Standard precautions for tadalafil still apply: avoid if taking nitrates, use caution with alpha-blockers or antihypertensives 1

Monitoring and Precautions

Blood Pressure Monitoring

• Check blood pressure before starting this combination
• Monitor for orthostatic hypotension (dizziness upon standing)
• Avoid alcohol (≥5 units) which can potentiate hypotensive effects 1

Cardiovascular Considerations

• Tadalafil should not be used if sexual activity is inadvisable due to cardiovascular status 7, 1
• The 2023 AHA/ACC guidelines emphasize avoiding tadalafil with nitrates due to severe hypotension risk, with a 24-hour washout for short-acting PDE5 inhibitors and 48 hours for tadalafil 7

Drug-Specific Warnings from FDA Label

• Seek emergency care if erection lasts >4 hours 1
• Stop tadalafil and seek medical attention for sudden vision or hearing loss 1
• Use caution with CYP3A4 inhibitors (beetroot has mild inhibitory effects) 1, 3

Common Pitfalls to Avoid

1. Don't confuse dietary nitrates with pharmaceutical nitrates: While pharmaceutical nitrates are absolutely contraindicated with tadalafil, dietary nitrates from beetroot pose a different, lower-level risk
2. Don't assume all tryptophan doses are dangerous with SSRIs: Your 33mg dose is nutritionally insignificant and poses minimal serotonin syndrome risk
3. Don't ignore cumulative blood pressure effects: The combination of beetroot (lowers BP ~5 mmHg) plus tadalafil (can lower BP) requires monitoring, especially if you're on other antihypertensives

Bottom Line

This combination can be used with appropriate monitoring, given the extremely low tryptophan dose and the distinction between dietary and pharmaceutical nitrates. The primary concern is additive blood pressure lowering from beetroot and tadalafil. Monitor blood pressure, watch for hypotensive symptoms, and consider spacing the supplements. The tryptophan dose is too low to pose meaningful serotonin syndrome risk with fluoxetine. The tadalafil-fluoxetine combination itself is well-studied and safe 5, 6.