Vasopressors and inotropes can cause hypertension, but remember that withdrawal of certain hypotensive agents (eg. clonidine, methyldopa) can cause rebound hypertension.

Drug interactions may lead to hypertension. Common culprits are monoamine oxidase inhibitors which interact with pethidine, ephedrine, and several other drugs.

Some illicit drugs, such as cocaine and ecstasy, may cause hypertensive reactions under anaesthesia. These too may interact with indirectly-acting sympathomimetics like ephedrine.

Systemic absorption of local anaesthetic/adrenaline mixtures can also cause hypertension.