randomized controlled trial found that sumatriptan may be able to prevent altitude sickness. Available forms All marketed triptans are available in oral form; some in form of sublingual tablets. Sumatriptan and zolmitriptan are also available as nasal sprays. For sumatriptan, a number of other application forms are marketed: suppositories, a subcutaneous injection, an iontophoretic transdermal patch, which uses low voltage controlled by a pre-programmed microchip to deliver a single dose of sumatriptan through the skin within 30 minutes; a drug-device combination containing sumatriptan powder that is "breath powered" allowing the user to blow sumatriptan powder in to their nostrils; as well as a needle-free injection system that works with air pressure. Contraindications All triptans are contraindicated in patients with cardiovascular diseases (coronary spasms, symptomatic coronary artery disease, after a heart attack or stroke, uncontrolled hypertension, Raynaud's disease, peripheral artery disease). Most triptans are also contraindicated during pregnancy and breastfeeding and for patients younger than 18; but sumatriptan and zolmitriptan nasal sprays are also approved for youths over 12. In spite of expert opinion and evidence to the contrary, the FDA and some other drug governance bodies have stated that monoamine oxidase inhibitors are contraindicated for sumatriptan, zolmitriptan and rizatriptan, and combination with ergot alkaloids such as ergotamine for all substances. At least two triptans (sumatriptan and rizatriptan) have been listed under the unacceptable medication by the Canadian Blood Services as a potential risk to the recipient; hence, donors are required not to have taken the medication for the last 72 hours. Adverse effects Triptans have few side effects if used in correct dosage and frequency. The most common adverse effect is recurrence of migraine. A systematic review found that "rizatriptan 10 mg was the only triptan with a recurrence rate greater than that of placebo". There is a theoretical risk of coronary spasm in patients with established heart disease, and cardiac events after taking triptans may rarely occur. Interactions Combination of triptans with other serotonergic drugs such as ergot alkaloids, monoamine oxidase inhibitors, selective serotonin reuptake inhibitors (SSRIs), serotonin–norepinephrine reuptake inhibitors (SNRIs) or St John's wort has been alleged to induce symptoms of a serotonin syndrome (a syndrome of changes in mental status, autonomic instability, neuromuscular abnormalities, and gastrointestinal symptoms), whereas scientific studies indicate there is no potential for life-threatening serotonin syndrome in patients taking triptans and SSRI or SNRIs at the same time, although the FDA has officially stated