Side Effects of Male Enhancement Pills: What Men Need to Know (2026)

By Jordan Harvey · 3 July 2026 · Updated 7 July 2026 · 13 min read

The biggest safety risk with male enhancement pills is not the side effects of the legitimate herbal ingredients listed on the label — it is what is on the label that is not declared. Between 2021 and 2025 the MHRA seized 19.5 million illegal erectile dysfunction pills in the UK, with £45 million worth of illegal medicines confiscated in 2025 alone (GOV.UK, 2026). A 2018 JAMA Network Open analysis of 776 adulterated dietary supplements found 45.5% were sexual-enhancement products, and 47% of those contained undeclared sildenafil or its analogues (Tucker et al., 2018).

This UK guide covers two distinct safety conversations that are usually conflated: the genuine, well-documented side effects of common supplement ingredients at clinical doses, and the far more serious adulteration risks from unregulated products. The first is mostly minor and predictable. The second is where men have ended up in A&E. Knowing which is which — and how to spot the difference before buying — is the practical safety question. For deeper context, see our evidence review of herbal supplements for men, the Shilajit guide, and the Tongkat Ali guide.

How Safe Are Herbal Supplements for Men at Standard Doses?

At supplement doses tested in published clinical trials, the seven most-used men’s health ingredients (Zinc, Tongkat Ali, Korean Ginseng, Maca, L-Arginine, Shilajit, Horny Goat Weed) generally have low rates of clinically significant adverse events. A systematic review of 44 RCTs covering 3,092 participants for ginseng alone reported no serious adverse events at clinical doses, with mild side effects (hot flashes, insomnia, dyspepsia) at rates within 1–2 percentage points of placebo (Kim et al., 2015). Tongkat Ali at 100–400mg/day has been studied for up to 9 months without serious adverse events (George & Henkel, 2014).

“Generally low” does not mean zero. The two variables that move side-effect risk meaningfully upward are individual susceptibility (existing conditions, age, body weight) and drug interactions. Men over 40 are more likely to be on prescription medication, which is why the wider supplement-safety picture in this demographic is dominated by interactions, not herbal toxicity.

Side Effects by Ingredient: What the Evidence Shows

1. Zinc

At the EFSA-aligned 10mg/day dose, side effects are uncommon. Higher doses (40mg+/day) over weeks can deplete copper, cause nausea, and reduce immune function paradoxically. Zinc gluconate or zinc citrate (Blue Power uses zinc as part of a balanced formula at 10mg, 100% NRV) is well tolerated. Long-term very-high-dose zinc >100mg/day has been linked to prostate concerns and is not appropriate for daily use.

2. Tongkat Ali

At 100–400mg/day of standardised hot-water extract, mild and uncommon side effects: nausea, abdominal discomfort, occasional headaches, and restlessness or insomnia if taken late in the day (the cortisol-modulating effect drives this). Rare cases of liver injury have been documented, predominantly in bodybuilders using high-dose or unverified products (NCBI LiverTox NBK609015). The 2021 EFSA novel-food assessment flagged genotoxicity in rats at 2,000mg/kg — roughly 700× clinical doses — but human data at 100–400mg/day shows acceptable safety. The wider safety profile is in our Tongkat Ali UK guide.

3. Korean Ginseng

Most commonly reported: insomnia (1.2% vs 0.7% placebo), followed by headache, mild hypertension, and occasional digestive upset (PubMed 12020172). The drug-interaction picture is the more important conversation: Korean ginseng can reduce warfarin’s effectiveness (clot risk), interact with MAOIs, and potentiate the blood-sugar-lowering effect of metformin and other diabetes medications (PMC6035379). Full ingredient profile in our Korean Ginseng benefits guide.

4. Maca Root

At 1,500–3,000mg/day (the doses used in published trials), maca has one of the cleanest safety profiles among the seven ingredients, with mild GI upset the most common side effect. There are no significant drug interactions documented at standard supplement doses.

5. L-Arginine

Common side effects include stomach pain, bloating, and diarrhoea. L-arginine can reactivate herpes simplex virus in susceptible individuals (cold sores or genital herpes). The most important safety signal is the blood-pressure interaction: L-arginine should not be combined with nitrate medications (GTN spray, isosorbide mononitrate) or PDE5 inhibitors (sildenafil, tadalafil) due to additive vasodilation that can drop blood pressure dangerously low (Mayo Clinic).

6. Shilajit

Purified shilajit at 250–500mg/day has a clean safety profile across published trials: a 2024 systematic review of 15 clinical studies covering 1,254 participants found no serious adverse events. The risks are concentrated in raw / unpurified shilajit: mycotoxin and heavy-metal contamination is documented in untested products. Always buy purified, third-party-tested shilajit. Detail in our Shilajit UK guide.

7. Horny Goat Weed

Despite the lack of strong human RCT evidence for efficacy, side-effect data from clinical use is broadly mild — nausea, dizziness, dry mouth, and rare cases of arrhythmia at very high doses. The bigger concern is product adulteration: horny goat weed products have been found among FDA-flagged adulterated supplements containing undeclared sildenafil.

Drug Interactions: The Risks Men Over 40 Need to Know

Drug interactions are where the supplement-safety conversation moves from minor to potentially serious. The interactions to flag with a GP or pharmacist before stacking herbal supplements:

The Hidden Ingredient Problem: What Is Really in Some Male Enhancement Products

This is where the safety conversation gets serious. The 2018 JAMA Network Open analysis of FDA enforcement data found 776 adulterated dietary supplements between 2007 and 2016, with 45.5% (353 products) marketed for sexual enhancement. The most commonly hidden pharmaceutical ingredient was sildenafil, found in 47% of tainted sexual products. Over 20% of tainted products contained more than one undeclared drug (Tucker et al., 2018).

Where the Safety Data Comes From: Funding & Independence

All major data sources cited in this safety guide are independent of the supplement industry:

In the US, dietary supplements as a category cause an estimated 23,005 emergency department visits and 2,154 hospitalisations per year (Geller et al., NEJM, 2015). The single most dangerous pattern in male-enhancement-specific ED visits is a man on nitrate medication unknowingly taking a “natural” supplement that secretly contains sildenafil — the resulting BP drop can be life-threatening.

How to Spot a Risky Product Before You Buy

Six red flags that tell you a supplement belongs to the high-risk side of the category:

• Claims that match prescription medicines (“works in 30 minutes”, “hours of hardness”, “harder than Viagra”) — food supplements legally cannot claim PDE5 inhibitor effects. If they do, hidden sildenafil is the usual reason
• No UK-registered company name or address on the website or label — the MHRA 2026 enforcement report identified marketplace and offshore sellers as the dominant source of seized product
• Proprietary “blends” hiding individual ingredient amounts — if the dose is hidden, comparison with the trial dose (and detection of adulteration) is harder
• No third-party Certificate of Analysis available on request — CoAs covering identity, heavy metals, microbial, and pharmaceutical adulterants are the structural defence here
• Marketplace listing (Amazon Marketplace, eBay, social-media direct sellers) without verifiable seller credentials
• Unrealistic pricing — standardised ingredients have a real cost. Products at 30–50% below the credible market price are often either underdosed or adulterated

How to Choose a Safe Male Enhancement Supplement: 6-Point Checklist

Why Does Blue Power’s Open-Dose Format Reduce These Risks?

Frequently Asked Questions About Male Enhancement Side Effects

The Bottom Line: How to Stay Safe with Male Enhancement Supplements

At standard supplement doses, the legitimate herbal ingredients used in men’s health products carry generally low rates of clinically significant side effects. The category’s real safety story is not in the well-studied ingredients on the label — it is in the hidden pharmaceuticals in unregulated products, and in the drug interactions that men over 40 are particularly exposed to. The MHRA’s 19.5 million pill seizures and the JAMA-documented 45.5% rate of adulteration in sexual-enhancement supplements are the structural backdrop to every safety decision.

The practical safety filter is consistent and easy to apply: UK or EU GMP certification, a third-party Certificate of Analysis, transparent per-ingredient milligram labelling, a UK-registered company with a real address, standardisation percentages on botanicals, and no medicinal claims. A product that meets all six is in a different safety bracket from a marketplace listing without any of them.

For men taking prescription medication — particularly nitrates, anticoagulants, BP medication, or PDE5 inhibitors — the most important supplement-safety habit is the simplest: take the full ingredient list to your GP or pharmacist before adding anything to your stack. The five-minute conversation prevents almost every supplement-related emergency presentation that ends up at A&E.