Trevor Cole (comics) - Weaknesses

Weaknesses

Symbiotes were naturally weakened by intense sounds and intense heat - especially large fires. For example, Spider-Man got the Venom symbiote off him using the intense sound of a church bell. Additionally, in some stories and games, (mostly mentioned in the 2000 Spider-Man video game), they are also weakened by magnesium. However, as each new symbiote has spawned a child, a natural evolution seems to not only increase their strengths, but also reduce their weaknesses. Even already existing symbiotes can mutate and develop these resistances. Still, there has not been an invulnerable symbiote in mainstream continuity, because the newest breeds can be harmed by incredible amounts of sonic waves and heat. Also, in the mainstream Marvel Universe, symbiotes are vulnerable to the heat produced by high voltage electricity.

There are other weaknesses as well besides sonics and heat. Iron Man managed to create an antidote formula that could destroy a symbiote (it should be noted that these were actually just virus-like biological organisms created by Doctor Doom, originally based on the Venom symbiote and were specially made as a bio-weapon). With Venom and Carnage, authorities have been able to keep the symbiotes in check with a chemical inhibitor. The criminal Styx nearly killed the Venom symbiote with his lethal touch. Whether a symbiote can mutate and reduce the effect of these weaknesses is unknown, although Carnage claimed to have developed invulnerability to sonics. Also, when a symbiote bonded with Wolverine, it was pushed out by his advanced healing factor, although Wolverine's healing factor had no use when he was bonded to a clone of the Venom symbiote.

In some incarnations, the symbiote is depicted as requiring a certain chemical (most likely phenethylamine) to stay sane and healthy, which has been said to be found abundantly in two sources: chocolate and human brain tissue. Thus, the host is forced to steal/buy large amounts of chocolate or become an unwilling cannibal who devours the brains of those he kills. This peculiar trait has only been witnessed in the Venom symbiote. However, both Carnage and Toxin have threatened their enemies with aspirations to "eating their brains", as well as various other body parts. When Toxin teamed up with Spider-Man and Black Cat, he struggled to keep himself together, telling Spider-Man that he was only "joking" about eating the robbers' brains.

On at least one occasion, Spider-Man was able to exhaust the symbiote by taking advantage of the fact that it made its webbing out of itself; after the symbiote had already used a great deal of webbing to bind him to a bell, Spider-Man forced the symbiote to use further webbing so that it would exhaust itself, like blood dripping from a wound (although the sheer amount of webbing that the symbiote would need to use for this weakness to be exploited makes its use in a fight limited).